treesit-forward-sexp (was: Make all tree-sitter modes optional)

[Juri Linkov]

> I'm using ruby-mode, at least for now, while all the wrinkles with
> indentation haven't been ironed out (and we'll probably not manage to get
> them all 100% right before the 29 release), and while ts modes don't
> support show-paren-mode like SMIE does. No proper sexp navigation, etc.

BTW, how ruby-ts-mode is intended to be used without proper sexp navigation?

I see that forward-sentence support for tree sitter was added recently
with treesit-forward-sentence.  There are also treesit-transpose-sexps,
treesit-beginning-of-defun and treesit-end-of-defun.

Are there any plans to add treesit-forward-sexp as well?

Currently I'm using such workaround:

```
(with-eval-after-load 'ruby-ts-mode
  (add-hook 'ruby-ts-mode-hook
            (lambda ()
              (smie-setup ruby-smie-grammar #'ruby-smie-rules
                          :forward-token  #'ruby-smie--forward-token
                          :backward-token #'ruby-smie--backward-token))))
```

Maybe something like this should be added to emacs-29
until treesit-forward-sexp is implemented in master?