Add Ernie-M Model to huggingface (#21349)

* config and tokenization(fast too) changed and ErnieEncoder added

* Slow Tokenization Added

* Tokenizer(slow) is now working and Fast Tokenizer removed

* Added Config code

* Added Base Model and utils

* ErnieMModel is now working

* All added except tests

* All tests passed except ErnieUIEM

* All tests passed

* all fixes done

* all fixes done

* fixed MAP

* fixed check_code_quality

* fixed Build PR Documentation issue

* Added changes(comments) and also updated to the latest upstream/main

* Added fixup

* Added # Copied comments

* Added fixup

* Added more comments and some nits

* Added fixup

* Fixed README_hd.md

* Added more fixes

* ErnieMTokenizer (being sentencepiece) protected and other docs edited

* Added code_quality fix

* Fixed for

* Added more fix

* modified AZ

* ernie-m tokenization test added!

* attention mask part fixed(with 0->self.config.pad_token_id)

* applied make fixup

utils/documentation_tests.txt

@@ -80,6 +80,8 @@ src/transformers/models/electra/configuration_electra.py
 src/transformers/models/electra/modeling_electra.py
 src/transformers/models/electra/modeling_tf_electra.py
 src/transformers/models/ernie/configuration_ernie.py
+src/transformers/models/ernie_m/configuration_ernie_m.py
+src/transformers/models/ernie_m/modeling_ernie_m.py
 src/transformers/models/flava/configuration_flava.py
 src/transformers/models/fnet/configuration_fnet.py
 src/transformers/models/fsmt/configuration_fsmt.py