Add Phi-1 and Phi-1_5 (#26170)

* only dir not even init

* init

* tokenizer removed and reference of codegen added

* modeling file updated a lot remaining app_rotary_emb

* conversion script done

* conversion script fixed, a lot of factoring done and most tests pass

* added token_clf and extractive_QA_head

* integration tests pass

* flash attn tests pass!

* config done

* more docs in modeling file

* some style fix

* style and others

* doc test error fix

* more doc fix

* some attention fixes

* most fixes

* style and other fixes

* docs fix and config

* doc fix

* some comments

* conversion script updated

* conversion script updated

* Revert "conversion script updated"

This reverts commit e92378c54084ec0747041b113083d1746ecb6c7f.

* final comments

* add Phi to language_modeling.md

* edit phi.md file

* rebase and fix

* removed phi-1.5 example

* changed model_type from 'phi'->'mixformer-sequential'

* small change

* small change

* revert \small change

* changed mixformer-sequential->phi

* small change

* added phi-1.5 example instead of phi-1

* doc test might pass now

* rebase and small change

* added the dropout layer

* more fixes

* modified .md file

* very very small doc change

docs/source/en/index.md

@@ -217,6 +217,7 @@ Flax), PyTorch, and/or TensorFlow.
 |                     [PEGASUS-X](model_doc/pegasus_x)                     |       ✅        |         ❌         |      ❌      |
 |                     [Perceiver](model_doc/perceiver)                     |       ✅        |         ❌         |      ❌      |
 |                     [Persimmon](model_doc/persimmon)                     |       ✅        |         ❌         |      ❌      |
+|                           [Phi](model_doc/phi)                           |       ✅        |         ❌         |      ❌      |
 |                       [PhoBERT](model_doc/phobert)                       |       ✅        |         ✅         |      ✅      |
 |                    [Pix2Struct](model_doc/pix2struct)                    |       ✅        |         ❌         |      ❌      |
 |                        [PLBart](model_doc/plbart)                        |       ✅        |         ❌         |      ❌      |