Add boundary checks for input validation (#28747)
This pull request introduces an important input validation in the
`multihead_attention_helper.h` file to ensure the integrity of the
`past_sequence_length` parameter. The main change is an additional check
that validates the value of `past_sequence_length` to prevent invalid or
out-of-bounds values.
**Input validation improvements:**
* Added a check to ensure that `past_sequence_length` is non-negative
and less than `max_sequence_length`, returning an error status if the
condition is not met in `Status CheckPast` in
`onnxruntime/contrib_ops/cpu/bert/multihead_attention_helper.h`.
