Fix most type hinting issues in library/lcd

[hchargois]

library/lcd was full of type hinting issues, which made the code light up like a (season-appropriate) Christmas tree in VSCode with Pylance 🎄

The same issues can be reported on the command-line with Pyright.

I've fixed (almost) all typing issues. I tried to keep the logic bug-for-bug compatible; except for Colors where I had to change a few things, and I took the opportunity to improve the parsing and now colors can be specified in more ways.

Sorry for the big MR, but there were a lot of intricate changes and it would have been hard to split it.

The only remaining typing issues in library/lcd are now the RGB-serialization methods in lcd_comm_{b,c,d}, which I didn't try to fix as I may try porting them to numpy later anyway.

[mathoudebine]

Thanks for the cleanup! I did not see the hinting issues since I do not use Pyright.
If you have time to fix the conflicts let me know when it's done so I can run the CI tests on your branch. I will not modify this file anymore for now

[hchargois]

@mathoudebine I've fixed the conflicts :)