Fixes#8242
Thought the issue this resolves was closed as "not planned", after further discussion, I was able to explain that the current priority breaks *some* template languages that rely on text existing inside of a `<[CDATA[` inside of a tag.
Additionally, this priority seems to be leftover from when this file was first committed, but there is no indication for why it is present, and it is possible it is a leftover from some debugging.
This change does not break existing injections that currently ship with `nvim-treesitter`, but instead allows additional injections to be defined by users, like those found in the Max/MSP Jitter XML Shader format.
Problem: Allowing undocumented "secret" (sub)captures makes it harder
to write comprehensive colorschemes and catch inconsistent captures.
Solution: Only allow captures listed in CONTRIBUTING.md. Add useful
(cross-language) subcaptures and drop language-specific or too niche
ones.
Follow-up: Adding further `*.builtin` captures and changing queries to
use them.
Language-specific subcaptures should instead be added in user config or
a custom language plugin.
