avm2: More work on the class refactor

[Lord-McSweeney]

This is work on storing a Class instead of a ClassObject as an Object's instance_of, which is necessary for the refactor.

Notable changes:

• ClassObject no longer stores its interfaces
• ClassObject no longer stores its type parameter, and the applications map is now a Option<Class> -> ClassObject map instead of an Option<ClassObject> -> ClassObject
• has_class_in_chain has been moved to Class
• Class now stores a list of all its interfaces (all_interfaces)
• ClassKey and ClassHashWrapper have been removed as they were no longer necessary after avm2: Simplify uses of GcCell<'gc, Class<'gc>> #16128
• VectorStorage now stores the value type as a Class instead of a ClassObject
• Logic for applying a type parameter to a ClassObject has been moved into its own function, ClassObject::parametrize

[torokati44]

Note that this did not auto-merge, because the Test Rust beta / ubuntu-22.04 check is required, and it's currently failing.
One way to fix it is #16682. It will probably be fixed in the next beta anyway (rust-lang/rust#126278), but that's six weeks from now.
Alternatively, a repo admin could just force-merge this of course.