Establish subtyping relationships for type extractors

[tobim]

📔 Description

This works already, but the checklist demands a bit more time investment.

📝 Checklist

• All user-facing changes have changelog entries.
• The changes are reflected on docs.tenzir.com/vast, if necessary. https://github.com/tenzir/event-horizon/pull/899
• The PR description contains instructions for the reviewer, if necessary.

🎯 Review Instructions

By commit.

[mavam]

Nice work. I looked a the code, unit test, and integration test.

I didn't give it a spin yet, though. It'd be great if someone else from @tenzir/backend could play with it for a few mins and try to break it.

[dominiklohmann]

Code and tests are fine by me. This seems to work nicely in practice—I've toyed around with this with a few simple tests and the output matched my expectations.