Improve PySequence objects

[n1t0]

With #530 we made most of the components expose their attributes and allow their modification. We'd like to do the same for PySequence objects (both for Normalizer and PreTokenizer sequences).

In order to make these PySequence objects behave like a list, we'd need to implement the PySequenceProtocol with the __len__, __getitem__ and __setitem__ dunder methods. Unfortunately, these don't support using a PyRef at the moment (cf PyO3/pyo3#1206), and we need it to access the content of the base class.

This is necessary to allow behavior such as:

if isinstance(tokenizer.normalizer, Sequence):
    # Access a normalizer in the sequence
    print(tokenizer.normalizer[0])
    # Modify a normalizer in the sequence
    tokenizer.normalizer[1] = Lowercase()

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[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.