fix: use is None instead of == None (PEP 8 E711)

[harshadkhetpal]

Summary

Replace == None with is None in two files under sagemaker-core/src/sagemaker/core/tools/ to comply with PEP 8 E711.

Using is / is not for None comparisons is the recommended Python idiom since None is a singleton.

Changes:

• resources_codegen.py line 646: if documentation == None: -> if documentation is None:
• templates.py line 647: elif value == None or not value: -> elif value is None or not value:

Testing

No behavior change — is None is semantically equivalent for None comparisons and is the PEP 8 recommended style.