Added support for electra tokenizer as a special case of BERT tokenizer

[KennethEnevoldsen]

Added support for the ELECTRA tokenizer. The ELECTRA models is waiting for the ELECTRA PR on curated transformers.

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran the tests, and all new and existing tests passed.
• My changes don't require a change to the documentation, or if they do, I've added all required information.
  • I have not added the documentation required for ELECTRA as it required the PR of curated transformers

[shadeMe]

Thanks for the PR! Just a couple of comments.

PS: The BuildKite CI failures can be ignored for now.

[KennethEnevoldsen]

Ah yes thanks for the suggestions (getting too used to ruff cleaning up after me). I also formatted it to black (saw that the tests failed).

[KennethEnevoldsen]

Hi @shadeMe seems like this PR is ready to merge?