bug#74963: Ambiguous treesit named and anonymous nodes in ruby-ts-mode

[Juri Linkov <juri@linkov.net>]

>   (setq-local treesit-thing-settings
>               `((ruby
>                  (sexp ,(cons (rx
>                                bol
>                                (or
>                                 "class"
>                                 ...
>                                 )
>                                eol)
>                               #'ruby-ts--sexp-p))

BTW, I just fixed a bug in typescript-ts-mode
where "string_fragment" was mismatched by "string",
because its regexp-opt matched node names too widely,
so needed to enclose in regexp anchors.

I see that all ts-modes solve this common problem each in its own way
(here 'list' indicates a list of strings that should match node names):

  c-ts-mode:    (regexp-opt list 'symbols)
  js-ts-mode:   (concat "\\_<" (regexp-opt list t) "\\_>")
  java-ts-mode: (rx (or list))
  ruby-ts-mode: (rx bol (or list) eol)

Currently there is no uniform way to handle this frequent need.
'concat' like above looks too ugly, but 'regexp-opt' with the
'symbols' arg produces a strange regexp for matching symbols.

Maybe better would be create a new argument for 'regexp-opt', e.g.:

  (regexp-opt list 'complete)

that will expand to:

  (concat "^" list "$")