Add proper T9 input support

[RichardHum]

This PR adds in proper T9 search, as compared to the current multi-tap approach. I've tested it and I haven't encountered any issues.

[brickbots]

Hello @RichardHum ! Thanks for this cool addition 👍

I've changed the merge base to main as this is our regular development branch where this will be merged and tested prior being added to a specific release. Sorry this has introduced a merge conflict, but it looks like it should be easy to resolve.

Please let me know me if you have any difficulty resolving the conflict, I'm happy to help!

[RichardHum]

Ah I should have read the documentation more closely. Since the WDS is so large, I'm working on some optimizations before submitting this for final review.

[RichardHum]

I added caching on the T9 letter->number mapping so it only needs to run once during the search.

Should be ready to merge now.

[brickbots]

Hi @RichardHum Sorry for the delay on this PR. I'd like to get this merged along with a host of other great QOL changes for a release in the next week or so. Are you able to resolve the minor conflict in textentry.py? Looking at its I don't think it's actually a conflict but just an artifact of the automerge

[RichardHum]

Should be resolved now