Fix/refresh respects session to fix job waiting

[aviruthen]

Fixes #5765 — wait=True (and other instance methods) ignore user-provided sagemaker_session, falling back to default/ambient credentials. Regenerated resources.py and shapes.py as this required fixes within the autogenerated files.

Problem
All 77 resource classes in resources.py are code-generated from templates. Class methods (create(), get()) accept a session parameter and use it correctly, but instance methods (refresh(), wait(), update(), delete(), stop()) call Base.get_sagemaker_client() with no session, creating a new default client. When a user passes a custom session (e.g., assumed-role via STS), the instance methods fail with NoCredentialsError.

Solution (codegen template fix)
Store the session on the resource instance in get(), and use it in all instance methods:

GET_METHOD_TEMPLATE: {resource}._session = session after instance creation
REFRESH_METHOD_TEMPLATE: Base.get_sagemaker_client(session=getattr(self, '_session', None))
UPDATE_METHOD_TEMPLATE (both variants): same
DELETE_METHOD_TEMPLATE: same
STOP_METHOD_TEMPLATE: changed from SageMakerClient().sagemaker_client to use Base.get_sagemaker_client(session=...)
Backward compatible — when no session is passed, _session is None, and get_sagemaker_client(session=None) behaves identically to the old get_sagemaker_client().

Additional codegen fixes (pre-existing bugs)
resources_codegen.py: Fixed _get_instance_count_ref indentation bug for TrainingJob that produced unparseable Python
resources_codegen.py: Aliased Session import as Boto3Session to avoid collision with generated Session resource class
shapes_codegen.py: Fixed _filter_input_output_shapes to not filter out shapes transitively referenced by resource classes (e.g., CreateEndpointConfigInput); fixed output path to write into shapes/ subdirectory instead of shadowing the package
codegen.py: Lazy import of reformat_file_with_black to avoid circular import; scoped black to generated files only

Testing
13 unit tests (test_session_propagation.py): verify _session stored on get(), used by refresh(), delete(), stop(), update(), backward compatibility with None
15 existing unit tests pass with no regressions
6 integration tests (test_session_wait_e2e.py): ProcessingJob wait, TrainingJob wait (via ModelTrainer and resource class), session survives refresh cycles, get-then-wait flow
Manual verification: TransformJob, Endpoint, and CompilationJob wait flows all confirmed working

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