LFM2 (#39340)

* [modeling][lfm2] LFM2 model on 4.53.0 interface

* [configuration] hook in LFM2 keys

* [modeling][lfm2] update modeling interface for 4.53.1

* [modeling][lfm2] apply mask to hidden conv states

* [misc] ruff format/lint

* [modeling][lfm2] minor: NotImplemented legacy cache conversion

* Create lfm2.md

* create nice modular

* style

* Update modeling_auto.py

* clean and start adding tests

* style

* Update test_modeling_lfm2.py

* Update __init__.py

* small test model size

* config

* small fix

* fix

* remove useless config attrs -> block_dim and conv_dim are hiden_size

* fix prepare inputs

* fix config

* test

* typo

* skip tests accordingly

* config docstrings

* add doc to .md

* skip config docstring check

---------

Co-authored-by: Maxime Labonne <81252890+mlabonne@users.noreply.github.com>
Co-authored-by: Cyril Vallez <cyril.vallez@gmail.com>

utils/check_config_attributes.py

@@ -32,6 +32,7 @@ transformers = direct_transformers_import(PATH_TO_TRANSFORMERS)
 CONFIG_MAPPING = transformers.models.auto.configuration_auto.CONFIG_MAPPING
 
 SPECIAL_CASES_TO_ALLOW = {
+    "Lfm2Config": ["full_attn_idxs", "tie_word_embeddings"],
     # used internally during generation to provide the custom logit processors with their necessary information
     "DiaConfig": [
         "delay_pattern",