Enable treesit-query-capture to return grouped captures

Enable treesit-query-capture to return grouped captures

This is needed for creating embedded parsers for embedded code
blocks of which language cannot be known ahead of time.  E.g.,
markdown and org mode's code block.

* src/treesit.c (Ftreesit_query_capture): Add parameter GROUPED.

(cherry picked from commit 625b2b02a3c9bad6d7abf57ea7f95ece29855906)