Implement auto derivation for scala 3

[jchyb]

Hello!
In this PR I reimplement the auto derivation features for scala 3 with full feature parity with the scala 2 counterpart. I reenable all of the tests for scala 3 as well, but still keep those in separate targets, as scala 3 requires explicit type annotations for implicits (if that is not a problem I can move those to the shared directory).

I tried to keep the reimplementation close to the shapeless counterpart, but instead I used:

• mirrors, which are similar to the shapeless generic method, in that they give us information about the case classes, their label names and types
• macros to reimplement the compile time information about the annotations and default values (we do cannot get those from mirrors, unfortunately)
• occcasionally match types, mainly where the PolyN functions were used