Add Wav2Vec2Conformer (#16812)

* save intermediate

* add wav2vec2 conformer

* add more code

* more

* first test passes

* make all checkpoints work

* update

* up

* more clean ups

* save clean-up

* save clean-up

* save more

* remove bogus

* finalize design conformer

* remove vision

* finish all tests

* more changes

* finish code

* add doc tests

* add slow tests

* fix autoconfig test

* up

* correct docstring

* up

* update

* fix

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Anton Lozhkov <aglozhkov@gmail.com>

* Update docs/source/en/model_doc/wav2vec2-conformer.mdx

* upload

* save copied from

* correct configs

* fix model outputs

* add to docs

* fix imports

* finish

* finish code

* correct copied from

* correct again

* correct make fix

* improve make fix copies

* save

* correct fix copy from

* correct init structure

* correct

* fix import

* apply suggestions

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Anton Lozhkov <aglozhkov@gmail.com>

docs/source/en/index.mdx

@@ -271,6 +271,7 @@ Flax), PyTorch, and/or TensorFlow.
 |             ViT             |       ❌       |       ❌       |       ✅        |         ✅         |      ✅      |
 |           ViTMAE            |       ❌       |       ❌       |       ✅        |         ✅         |      ❌      |
 |          Wav2Vec2           |       ✅       |       ❌       |       ✅        |         ✅         |      ✅      |
+|     Wav2Vec2-Conformer      |       ❌       |       ❌       |       ✅        |         ❌         |      ❌      |
 |            WavLM            |       ❌       |       ❌       |       ✅        |         ❌         |      ❌      |
 |            XGLM             |       ✅       |       ✅       |       ✅        |         ❌         |      ✅      |
 |             XLM             |       ✅       |       ❌       |       ✅        |         ✅         |      ❌      |