Add tf_keras imports to prepare for Keras 3 (#28588)

* Port core files + ESM (because ESM code is odd)

* Search-replace in modelling code

* Fix up transfo_xl as well

* Fix other core files + tests (still need to add correct import to tests)

* Fix cookiecutter

* make fixup, fix imports in some more core files

* Auto-add imports to tests

* Cleanup, add imports to sagemaker tests

* Use correct exception for importing tf_keras

* Fixes in modeling_tf_utils

* make fixup

* Correct version parsing code

* Ensure the pipeline tests correctly revert to float32 after each test

* Ensure the pipeline tests correctly revert to float32 after each test

* More tf.keras -> keras

* Add dtype cast

* Better imports of tf_keras

* Add a cast for tf.assign, just in case

* Fix callback imports

tests/models/esm/test_modeling_tf_esm.py

@@ -30,6 +30,7 @@ if is_tf_available():
     import numpy
     import tensorflow as tf
 
+    from transformers.modeling_tf_utils import keras
     from transformers.models.esm.modeling_tf_esm import (
         TF_ESM_PRETRAINED_MODEL_ARCHIVE_LIST,
         TFEsmForMaskedLM,
@@ -269,7 +270,7 @@ class TFEsmModelTest(TFModelTesterMixin, PipelineTesterMixin, unittest.TestCase)
 
         for model_class in self.all_model_classes:
             model = model_class(config)
-            assert isinstance(model.get_input_embeddings(), tf.keras.layers.Layer)
+            assert isinstance(model.get_input_embeddings(), keras.layers.Layer)
             if model_class is TFEsmForMaskedLM:
                 # Output embedding test differs from the main test because they're a matrix, not a layer
                 name = model.get_bias()