Modified generator to generate plugins

[saimedhi]

Description

Modified the generator to generate plugins. Currently, it generates KNN APIs. I will add integration tests.

• Generated unit tests for all generated APIs is still pending and need to be done.

Issues Resolved

Closes #693
Closes #697

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.14%. Comparing base (b2a1796) to head (39273af).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #700   +/-   ##
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  Coverage   72.14%   72.14%           
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  Files          89       89           
  Lines        7945     7945           
=======================================
  Hits         5732     5732           
  Misses       2213     2213           

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[saimedhi]

Lint is failing. I will fix it in spec.

************* Module opensearchpy._async.plugins.knn
opensearchpy/_async/plugins/knn.py:232:8: C0103: Argument name "nodeId" doesn't conform to snake_case naming style (invalid-name)
************* Module opensearchpy.plugins.knn
opensearchpy/plugins/knn.py:[23](https://github.com/opensearch-project/opensearch-py/actions/runs/8364328461/job/22899396250?pr=700#step:5:24)2:8: C0103: Argument name "nodeId" doesn't conform to snake_case naming style (invalid-name)

[saimedhi]

READY FOR REVIEW.

• I'll include the generated KNN plugin and integration tests in the upcoming PR.

Currently facing issues with testing train_model, which are unrelated to the client. Followed documentation while writing tests.

knn train_model response {'model_id': 'my-model'}

knn get_model response {'model_id': 'my-model', 'model_blob': '', 'state': 'failed', 
'timestamp': '2024-03-22T06:44:52.102263Z', 'description': 'My model description', 
'error': 'Failed to execute training. May be caused by an invalid method definition 
or not enough memory to perform training.', 'space_type': 'l2', 'dimension': 4, 'engine': 'faiss'}

• All KNN plugin generated APIs are functional and callable.

[dblock]

This works. After you merge this you should refactor it.

Replace is_plugin by inheritance. Create a base class called Component (or another name) and a new class called Plugin inherits from it. Make Module inherit from it as well. The extra functionality of a plugin or module goes into the child classes, and everything common into the base class.