[breaking|pipelines|tokenizers] Adding slow-fast tokenizers equivalence tests pipelines - Removing sentencepiece as a required dependency (#8073)

* Fixing roberta for slow-fast tests

* WIP getting equivalence on pipelines

* slow-to-fast equivalence - working on question-answering pipeline

* optional FAISS tests

* Pipeline Q&A

* Move pipeline tests to their own test job again

* update tokenizer to add sequence id methods

* update to tokenizers 0.9.4

* set sentencepiecce as optional

* clean up squad

* clean up pipelines to use sequence_ids

* style/quality

* wording

* Switch to use_fast = True by default

* update tests for use_fast at True by default

* fix rag tokenizer test

* removing protobuf from required dependencies

* fix NER test for use_fast = True by default

* fixing example tests (Q&A examples use slow tokenizers for now)

* protobuf in main deps extras["sentencepiece"] and example deps

* fix protobug install test

* try to fix seq2seq by switching to slow tokenizers for now

* Update src/transformers/tokenization_utils_base.py

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Update src/transformers/tokenization_utils_base.py

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

src/transformers/data/processors/squad.py

@@ -8,7 +8,7 @@ from tqdm import tqdm
 
 from ...file_utils import is_tf_available, is_torch_available
 from ...tokenization_bert import whitespace_tokenize
-from ...tokenization_utils_base import PreTrainedTokenizerBase, TruncationStrategy
+from ...tokenization_utils_base import BatchEncoding, PreTrainedTokenizerBase, TruncationStrategy
 from ...utils import logging
 from .utils import DataProcessor
 
@@ -765,6 +765,7 @@ class SquadFeatures:
         token_to_orig_map: mapping between the tokens and the original text, needed in order to identify the answer.
         start_position: start of the answer token index
         end_position: end of the answer token index
+        encoding: optionally store the BatchEncoding with the fast-tokenizer alignement methods.
     """
 
     def __init__(
@@ -784,6 +785,7 @@ class SquadFeatures:
         end_position,
         is_impossible,
         qas_id: str = None,
+        encoding: BatchEncoding = None,
     ):
         self.input_ids = input_ids
         self.attention_mask = attention_mask
@@ -803,6 +805,8 @@ class SquadFeatures:
         self.is_impossible = is_impossible
         self.qas_id = qas_id
 
+        self.encoding = encoding
+
 
 class SquadResult:
     """