TF model cards (#14720)

* Initial commit for Keras model cards

* Revert accidental change

* make style

* make style

* make style

* Fix PR comments

* Move repo creation to __init__

* Fixes to README.md creation

* Partial progress for proper card creation on `push_to_hub`

* Proper card creation from `push_to_hub` plus fixes for malformed model cards

* Fixes for model card creation outside the callback

* Adding a model card creation test

* Putting the model card creation test in the right file.
Good job, Matt.

* make style

* Fix model card test temp dir usage

* Fix model card creation when no optimizer present

* Fixes for when training history not present

* Fix accidental edit to test_modeling_common

tests/test_modeling_tf_common.py

@@ -1386,6 +1386,15 @@ class TFModelPushToHubTester(unittest.TestCase):
                     models_equal = False
             self.assertTrue(models_equal)
 
+    def test_push_to_hub_with_model_card(self):
+        config = BertConfig(
+            vocab_size=99, hidden_size=32, num_hidden_layers=5, num_attention_heads=4, intermediate_size=37
+        )
+        model = TFBertModel(config)
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            model.push_to_hub(os.path.join(tmp_dir, "test-model-tf"))
+            self.assertTrue(os.path.isfile(os.path.join(tmp_dir, "test-model-card-tf", "README.md")))
+
     def test_push_to_hub_in_organization(self):
         config = BertConfig(
             vocab_size=99, hidden_size=32, num_hidden_layers=5, num_attention_heads=4, intermediate_size=37