[tests] add attention backend tests. (#13174)
* add attention backend tests.
* remove existing tests/others/test_attention_backends.py file
* modify generate_model_tests.py
* remove native.
* account for _keep_in_fp32_modules
* don't skip when exception is raised.
* use is_kernels_available()
* mark with compile.
* move rtol and atol to methods as defaults.
* Apply suggestions from code review
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
* up
* up
