Refactor Autoimport database and indexing

[bagel897]

Description

The main autoimport class has gotten quite large. This PR simplifies it by splitting out a Database object. It also adds an index function to unify indexing between the different methods (resource, gen_cache, modules_cache)

Future Proposals

This can be iterated on in future PRs

• Simplify the constructor in the Database class (Combine with create_connection/setup_db??)
• Split out the searching component somehow?
• Split the indexing component? (IE, a core indexer with the _index function, a package discovery mechanism, and the rope API)

Checklist (delete if not relevant):

• I have added tests that prove my fix is effective or that my feature works
• I have updated CHANGELOG.md
• I have made corresponding changes to user documentation for new features
• I have made corresponding changes to library documentation for API changes

[lieryan]

Hi @bagel897, is this PR ready for review or are you still working on it? If it's ready to review, can you please move it out of draft?

[bagel897]

Still have stuff to work on and will need to incorporate #516 once its merged.