Feature Request: Fuzzy CompletionType option

[Jacobious52]

It would be neat and useful to have another CompletionType option that uses fuzzy searching, similar to functionality that provides fzf. I have a branch that uses skim to filter and select the completion as a proof of concept, but want to make sure this is a feature that would fit in rustyline. I imagine it would be an optional cargo feature as it adds more dependencies.

Here's an example using nushell which uses rustyline with my branch with fuzzy completion.

There's still some polish and some undesired behaviour, for example my current implementation adds a new line to the prompt. Not sure how to make it replace the existing line instead.

If this is a feature that would be useful, I'm happy to PR with some guidance on polishing the implementation.

This fuzzy search would also be useful for (reverse-i-search) mode, but I haven't gotten that far in the implementation yet.

Cheers

[Jacobious52]

Closed with #326