Change how "additional_special_tokens" argument in the ".from_pretrained" method of the tokenizer is taken into account (#13056)

* add test

* add change in PretrainedTokenizerBase

* change Luke

* deactivate

* add the possibility to add additional special tokens for M2M100

* format

* add special test for canine

* proposed changes for mbart

* proposed changes for mbart50

* proposed changes for byt5

* proposed changes for canine

* proposed changes for t5

* test fast and slow

* remove comment

* remove comment

* add fast version for all tests

* replace break by continue

* add more comments

* add check to avoid duplicates

* remove comment

* format

* proposed change for wave2vec2

* reverse changes mbart

* uncomment

* format

tests/test_processor_wav2vec2.py

@@ -53,8 +53,9 @@ class Wav2Vec2ProcessorTest(unittest.TestCase):
         with open(self.feature_extraction_file, "w", encoding="utf-8") as fp:
             fp.write(json.dumps(feature_extractor_map) + "\n")
 
-    def get_tokenizer(self, **kwargs):
-        kwargs.update(self.add_kwargs_tokens_map)
+    def get_tokenizer(self, **kwargs_init):
+        kwargs = self.add_kwargs_tokens_map.copy()
+        kwargs.update(kwargs_init)
         return Wav2Vec2CTCTokenizer.from_pretrained(self.tmpdirname, **kwargs)
 
     def get_feature_extractor(self, **kwargs):