* Show warning if multiple type boxes are used
* Report templates referencing media in Media Check
* Apply suggestions from code review
* Fix media-check.ftl
* Only report media references with fields
Like `<img src={{Front}}>`.
Also report Anki sound tags and latex.
* Loop existing media regexes
Combine existing check for unparsable templates with a check for unknown
field names and a check for front sides without any field replacement.
Updating the notetype's fields now mutates the parsed templates, so the
checks can run on the final templates.
Older translations will note have the $notetype variable, but that is
not an error in Fluent - it would only cause problems if we tried to
use the new string on older Anki versions.
