Problem: Outdated query files in `runtimepath` can trigger errors
which are hard to diagnose.
Solution: Add section to `:check treesitter` that lists all query
files in `runtimepath`, sorted by language and query type. Files
are listed in `runtimepath` order so that the first of multiple entry
is typically the one that is used.
Note: Unlike the `nvim-treesitter` health check, this does not try
to parse the queries so will not flag incompatible ones (which would
be much more expensive).