Validate PackedMultiHeadAttention token offsets (#33098)
This pull request introduces validation for the `token_offset` input in
the unfused `PackedMultiHeadAttention` CUDA operator, ensuring that all
token offsets are within valid bounds. It adds a CUDA kernel for
validation, integrates the check into the operator's logic, updates the
operator schema documentation, and adds unit tests to verify the new
validation logic.
**Token Offset Validation for Unfused PackedMultiHeadAttention:**
* Added a CUDA kernel (`ValidateTokenOffsetKernel`) and a new function
(`ValidatePackedMultiHeadAttentionTokenOffset`) to validate that all
`token_offset` values are within the range `[0, batch_size *
sequence_length)`. If any value is out of bounds, the function returns
an error.
(`onnxruntime/contrib_ops/cuda/bert/packed_multihead_attention_impl.cu`
[[1]](diffhunk://#diff-9bea87ca89683be050b0ae0961002626bfae523bea1c01acf0548e0389eeb86fR35-R81)
`onnxruntime/contrib_ops/cuda/bert/packed_multihead_attention_impl.h`
[[2]](diffhunk://#diff-0eb9ea035b0eac06d711eb187fbaf2ccf3d4165e5f25ab90db2b515b476f8991R16-R21)
* Integrated the validation function into the unfused backend path of
the `PackedMultiHeadAttention` operator, ensuring the check is performed
before computation proceeds.
(`onnxruntime/contrib_ops/cuda/bert/packed_multihead_attention.cc`
[onnxruntime/contrib_ops/cuda/bert/packed_multihead_attention.ccR226-R235](diffhunk://#diff-0941dabf2a66e4f3e090c3c3562e2a493cf5daf905bfa1bd398f513f22ec708eR226-R235))
**Operator Documentation:**
* Updated the operator schema documentation to specify that
`token_offset` values must be in `[0, batch_size * sequence_length)`.
(`onnxruntime/core/graph/contrib_ops/bert_defs.cc`
[onnxruntime/core/graph/contrib_ops/bert_defs.ccL1024-R1025](diffhunk://#diff-8bf31275168b1e4a2aecd6760acf0ef92347134b003dfdc687c5d3cec4a178ecL1024-R1025))
**Testing:**
* Added new unit tests to verify that invalid `token_offset` values in
the unfused CUDA implementation are correctly detected and produce the
expected error.
(`onnxruntime/test/contrib_ops/packed_multihead_attention_op_test.cc`
[onnxruntime/test/contrib_ops/packed_multihead_attention_op_test.ccR409-R462](diffhunk://#diff-c9634e9e2e9f2e69fd8c37c98888127f9417f69f340e8dbc5dd21815328be59bR409-R462))
