PhiMoE (#33363)
* onboard phimoe model
* removed debug code
* added unit tests
* updated docs
* formatted
* fixed unit tests
* fixed test case
* fixed format
* refactored code
* fixed expected outputs in the integration tests
* Added a warning msg
* Addressed comments
* Addressed comments
* fixed test cases
* added paper link
* Addressed comments
* Refactored PhimoeForCausalLM forward fn
* Refactored PhimoeRotaryEmbedding class
* fixed test cases
* fixed testcase
* fixed test case
* Addressed comments
* fixed test cases
* fixed testcases
* Used cache position instead to get the seq len
