[legacy] move unused and outdated codes to legacy

[ver217]

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1. Move trainer, engine, builder and registry to legacy folder, as these codes are not used anymore and have equivalent substitution.
2. Update related docs.
3. Move related tests to tests/test_legacy. And this folder is ignored in CI.

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• I have added thorough tests.
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[github-actions]

The code coverage for the changed files is 48%.

Click me to view the complete report

Name                                                                               Stmts   Miss  Cover
------------------------------------------------------------------------------------------------------
colossalai/auto_parallel/tensor_shard/node_handler/registry.py                        19     19     0%
colossalai/context/parallel_context.py                                               227     13    94%
colossalai/context/process_group_initializer/initializer_1d.py                        29      0   100%
colossalai/context/process_group_initializer/initializer_2d.py                        72      1    99%
colossalai/context/process_group_initializer/initializer_2p5d.py                     136      2    99%
colossalai/context/process_group_initializer/initializer_3d.py                       155      1    99%
colossalai/context/process_group_initializer/initializer_data.py                      27      0   100%
colossalai/context/process_group_initializer/initializer_model.py                     28      0   100%
colossalai/context/process_group_initializer/initializer_pipeline.py                  26      0   100%
colossalai/context/process_group_initializer/initializer_sequence.py                  42      0   100%
colossalai/context/process_group_initializer/initializer_tensor.py                    27      0   100%
colossalai/initialize.py                                                             188     77    59%
colossalai/legacy/__init__.py                                                          0      0   100%
colossalai/legacy/builder/__init__.py                                                  2      0   100%
colossalai/legacy/builder/builder.py                                                  21      5    76%
colossalai/legacy/engine/__init__.py                                                   3      0   100%
colossalai/legacy/engine/_base_engine.py                                              90     23    74%
colossalai/legacy/engine/gradient_accumulation/__init__.py                            15      2    87%
colossalai/legacy/engine/gradient_accumulation/_gradient_accumulation.py             107     39    64%
colossalai/legacy/engine/gradient_handler/__init__.py                                  7      0   100%
colossalai/legacy/engine/gradient_handler/_base_gradient_handler.py                    8      1    88%
colossalai/legacy/engine/gradient_handler/_data_parallel_gradient_handler.py          10      0   100%
colossalai/legacy/engine/gradient_handler/_moe_gradient_handler.py                    20      9    55%
colossalai/legacy/engine/gradient_handler/_pipeline_parallel_gradient_handler.py      24     14    42%
colossalai/legacy/engine/gradient_handler/_sequence_parallel_gradient_handler.py      10      2    80%
colossalai/legacy/engine/gradient_handler/_zero_gradient_handler.py                    6      1    83%
colossalai/legacy/engine/gradient_handler/utils.py                                    21      0   100%
colossalai/legacy/engine/schedule/__init__.py                                          4      0   100%
colossalai/legacy/engine/schedule/_base_schedule.py                                   76     55    28%
colossalai/legacy/engine/schedule/_non_pipeline_schedule.py                           30     20    33%
colossalai/legacy/engine/schedule/_pipeline_schedule.py                              430    397     8%
colossalai/legacy/engine/schedule/_pipeline_schedule_v2.py                            78     78     0%
colossalai/legacy/registry/__init__.py                                                17      0   100%
colossalai/legacy/registry/registry.py                                                31     10    68%
colossalai/legacy/trainer/__init__.py                                                  2      2     0%
colossalai/legacy/trainer/_trainer.py                                                170    170     0%
colossalai/legacy/trainer/hooks/__init__.py                                            6      6     0%
colossalai/legacy/trainer/hooks/_base_hook.py                                         34     34     0%
colossalai/legacy/trainer/hooks/_checkpoint_hook.py                                   31     31     0%
colossalai/legacy/trainer/hooks/_commons_.py                                           7      7     0%
colossalai/legacy/trainer/hooks/_log_hook.py                                         145    145     0%
colossalai/legacy/trainer/hooks/_lr_scheduler_hook.py                                 21     21     0%
colossalai/legacy/trainer/hooks/_metric_hook.py                                      227    227     0%
colossalai/nn/layer/parallel_1d/layers.py                                            474    178    62%
colossalai/nn/layer/parallel_2d/layers.py                                            484    183    62%
colossalai/nn/layer/parallel_2p5d/layers.py                                          477    173    64%
colossalai/nn/layer/parallel_3d/layers.py                                            513    431    16%
colossalai/nn/layer/parallel_sequence/layers.py                                       92     70    24%
colossalai/nn/layer/vanilla/layers.py                                                147     59    60%
colossalai/nn/loss/loss_1d.py                                                         59      8    86%
colossalai/nn/loss/loss_2d.py                                                         74      8    89%
colossalai/nn/loss/loss_2p5d.py                                                       74      8    89%
colossalai/nn/loss/loss_3d.py                                                         81     55    32%
colossalai/nn/loss/loss_moe.py                                                        24     12    50%
colossalai/nn/lr_scheduler/cosine.py                                                  30     15    50%
colossalai/nn/lr_scheduler/linear.py                                                  12      6    50%
colossalai/nn/lr_scheduler/multistep.py                                               16      6    62%
colossalai/nn/lr_scheduler/onecycle.py                                                 7      2    71%
colossalai/nn/lr_scheduler/poly.py                                                    21     10    52%
colossalai/nn/lr_scheduler/torch.py                                                   21      4    81%
colossalai/nn/optimizer/cpu_adam.py                                                   68      4    94%
colossalai/nn/optimizer/fused_adam.py                                                 55     10    82%
colossalai/nn/optimizer/fused_lamb.py                                                 82     74    10%
colossalai/nn/optimizer/fused_sgd.py                                                  60     50    17%
colossalai/nn/optimizer/hybrid_adam.py                                                63      4    94%
colossalai/nn/optimizer/lamb.py                                                       54     47    13%
colossalai/nn/optimizer/lars.py                                                       55     46    16%
colossalai/utils/data_sampler/data_parallel_sampler.py                                58      8    86%
colossalai/utils/profiler/profiler.py                                                 62     62     0%
colossalai/utils/profiler/stateful_tensor_mem_extention.py                            92     92     0%
colossalai/zero/legacy/gemini/ophooks/_shard_grad_ophook.py                           19     19     0%
colossalai/zero/legacy/gemini/ophooks/_shard_param_ophook.py                          33     33     0%
colossalai/zero/legacy/sharded_model/zero_hook.py                                     73     50    32%
tests/test_booster/test_plugin/test_gemini_plugin.py                                  72      9    88%
tests/test_pipeline/test_cuda_rpc_performance.py                                      48     31    35%
------------------------------------------------------------------------------------------------------
TOTAL                                                                               6129   3179    48%

[TongLi3701]

Thanks.