[red-knot] record dependencies when resolving across imports

[carljm]

Summary

Record dependencies when resolving type of a symbol that depends on type of another symbol.

If a symbol in another module can't be resolved, then we record a dependency on the entire module (if it changes, maybe then the type can be resolved, so we would need to invalidate.)

Also corrects unnecessary mutable references to db/jar/type_store. (I know this was done in another outstanding PR too, but it was bugging me so I did it here too; I don't mind rebasing if the other one lands first.)

Test Plan

cargo test

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[carljm]

I don't think I'm going to merge this as-is, want to redo it based on further discussion, and also depends on the salsa-or-no-salsa decision.