Add the keyword ':copy-queries' to 'treesit-language-source-alist'.

Add the keyword ':copy-queries' to 'treesit-language-source-alist'.

* lisp/treesit-x.el (define-treesit-generic-mode): Add keyword
':copy-queries t' to the end of 'source'.

* lisp/treesit.el (treesit-language-source-alist):
Document the keyword ':copy-queries'.
(treesit--install-language-grammar-1): Add &rest args.
Process the keyword args.  Call 'treesit--copy-queries'
when :copy-queries is non-nil.
(treesit--copy-queries): Add arg 'source-dir'.  Copy queries
from source-dir as well.  Copy only the file "highlights.scm".

(cherry picked from commit 261a965ff1a423c9dc0ee7c89974e4fc3c16b863)