Problem: Sharing queries with upstream and Helix is difficult due to
different capture names.

Solution: Define and document a new set of standard captures that
matches tree-sitter "standard captures" (where defined) and is closer to
Helix' Atom-style nested groups.

This is a breaking change for colorschemes that defined highlights based
on the old captures. On the other hand, the default colorscheme now
defines links for all standard captures (not just those used in bundled
queries), improving the out-of-the-box experience.