Implement compile-time caching for Scala 3

[neko-kai]

We use caching to speed up LightTypeTag creation on Scala 2, we might want to port this technique to Scala 3 implementation also.

We can also Scala 2 improve Scala 2 caching, e.g. right now we cache individual AbstractReference's, but we don't cache basesDb or InheritanceDb (or we could cache the entire serialized LTT instead)