feature request: support for UTF-8 and UTF-32 with position encodings

[jokeyrhyme]

Howdie!

Firstly, I want to thank you so much for sharing this library! <3

I have successfully integrated this with tower-lsp in my language server project: https://github.com/jokeyrhyme/nuls

I did want to discuss and register here that I'm interested in expanding the support for more position encodings, but I'm honestly not sure yet which editors do not support UTF-16

I'm not sure when I'll have the time to do this work, but I'm happy to give it a try if that's something you think is in-scope for this project

Cheers!

[GiveMe-A-Name]

Currently, this library only supports UTF-16. However, we also need support for UTF-8 and UTF-32. In fact, I had planned to add this support before, but I wasn't sure if any projects required it, so I postponed the work.

I would appreciate it if you could work on this and submit a PR whenever you have some free time.
If you're not in a hurry, I will implement it at a later time.

[jokeyrhyme]

This looks promising: https://crates.io/crates/widestring