This PR introduces the concept of hierarchical tags - that is, each tag can belong to a parent tag
I haven't done any work to improve the tag include/exclude filtering in the search settings UI just yet. Need to give that some more thought, but the backend side of these changes can be done now
Checklist
[x] I have installed pre-commit and run the hooks with pre-commit run.
[x] I have updated any related tests for code I modified or added new tests where appropriate.
[x] I have updated any relevant documentation or created new documentation where appropriate.
Description
Checklist
pre-commitand run the hooks withpre-commit run.