Fix source tokens for HF fast tokenizers

[ddaspit]

• update MT tutorial to demonstrate TranslationResult
• incompatible with transformers>=4.42, because of breaking change in NLLB tokenizer

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This change is 

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.07%. Comparing base (ca7fba2) to head (6f240b6).

Files with missing lines	Patch %	Lines
...translation/huggingface/hugging_face_nmt_engine.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #133      +/-   ##
==========================================
- Coverage   88.07%   88.07%   -0.01%     
==========================================
  Files         273      273              
  Lines       16039    16041       +2     
==========================================
+ Hits        14127    14128       +1     
- Misses       1912     1913       +1     

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[johnml1135]

[johnml1135]

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ddaspit)