[GSProcessing] Add option to truncate vectors with no-op transformation.

[thvasilo]

Issue #, if available:

Description of changes:

• We add a keyword argument to the GSProcessing no-op transformation, named truncate_dim. When a user provides this parameter, we will try to truncate the input vectors to the dimension specified. This allows users to easily make use of input Matryoshka embeddings.
• (Revision) Added the same transformation for GConstruct.

Testing

Unit tests passing, unit and integration test added for the new transformation option.

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[jalencato]

Some small comment

[thvasilo]

Added GCosntsruct support @jalencato let me know if there's something missing for config parsing. I couldn't find any gconstruct docs in the current doc structure, they'll need to be added later or we can rebase this PR once those are added back.

[jalencato]

Added GCosntsruct support @jalencato let me know if there's something missing for config parsing. I couldn't find any gconstruct docs in the current doc structure, they'll need to be added later or we can rebase this PR once those are added back.

It should be just about the feature transformation configuration for GConstruct: https://graphstorm.readthedocs.io/en/latest/configuration/configuration-gconstruction.html#configurations-gconstruction

And for the files on Github: https://github.com/awslabs/graphstorm/blob/main/docs/source/configuration/configuration-gconstruction.rst.

Changing the content here will not affect the doc refactor as we always to the entire doc when doing the refactor.

[jalencato]

LGTM