GQA Flash Attention with Attention Mask (#18283)
### Description
GQA now only works with Flash Attention with Attention Mask input,
allowing for batched input. Note: This PR Disables Memory Efficient
Attention, only allowing Flash Attention kernel to be used.
### Motivation and Context
Allows GQA to work with batched input.
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Co-authored-by: Yufeng Li <liyufeng1987@gmail.com>
