Use scaled_dot_product_attention within attention.cpp (#87312)
# Summary
Use the private _scaled_dot_product_attention to support _native_multiheaded_attention. _SDP provides access to fused kernels when certain conditions are meant enabling a speed up for MHA.
cc @cpuhrsch @jbschlosser @bhosmer @mikaylagawarecki
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87312
Approved by: https://github.com/cpuhrsch
