Support for emacs 29's built-in `treesit` library

[rweir]

Hi!

As you probably know, emacs29 includes built in support for tree-sitter grammars with a library called treesit. Unfortunately it's incompatible with the older out-of-tree tree-sitter.el that this package is based on. Are you interested in porting it / would you accept a patch to port it, which would make this package only work on emacs 29+?

[jcs090218]

Yes, I would like to support the built-in treesit. However, I am still using the external package tree-sitter.el, so it will take a while. But I do accept PRs as long as this package still supports the tree-sitter.el. Therefore, the best approach is to support them both in this package.