[CI]: Consider More Detailed JinJa2 Template Linting and Checking

After doing numerous JinJa2 template PRs and test file regeneration (_and getting caught by a nasty indentation bug_), it feels like we could benefit from setting up some linting rules and checks for JinJa2 templates that are a bit more detailed and custom. Right now, we check that the files will produce test files that can be linted by Black, but we don't _really_ do much additional validation.

Marking this as a discussion, since I haven't formed many more thoughts that that around this issue. But I anticipate both more contributors and more changes to templates going forward, so thought I'd make a note here of what I have found so far:

[curlylint](https://www.curlylint.org/docs/rules/all)
[Jinjalint](https://causlayer.orgs.hk/motet-a/jinjalint)