Validate SkipLayerNorm prepacked lengths (#31676)
This pull request improves the robustness and correctness of the
`SkipLayerNorm` operator in ONNX Runtime by adding stricter validation
of prepacked tensor sizes and enhancing test coverage for these checks.
The changes ensure that mismatches in tensor dimensions are detected
early, preventing potential runtime errors.
**Validation and Error Checking Enhancements:**
* Added explicit size validation for prepacked tensors (`skip`, `gamma`,
`beta`, `bias`) in `SkipLayerNorm::Compute`, ensuring their lengths
match the expected `hidden_size` and providing clear error messages when
mismatches occur.
* Introduced new member variables to track the sizes of prepacked
`gamma`, `beta`, and `bias` tensors, and updated their management in the
constructor and `PrePack` method.
[[1]](diffhunk://#diff-efe341d72f1c3c6bf27021372beaeb3f0dee45cff488d5f2917a1a9ad2219375R117-R119)
[[2]](diffhunk://#diff-2b3c9f0e42906b33f0eba5c151270bd7c7f89ab6f80729f5af16ca3bf4d49482R25-R27)
[[3]](diffhunk://#diff-efe341d72f1c3c6bf27021372beaeb3f0dee45cff488d5f2917a1a9ad2219375R291-R305)
**Testing Improvements:**
* Added two new unit tests to verify that the operator correctly rejects
prepacked tensors with incorrect sizes for `gamma` and `skip`,
confirming that the new validation logic works as intended.
Co-authored-by: Copilot <223556219@users.noreply.github.com>
