Harness the dialyzer for the private clients 🐴

In this release, all warnings of the dialyzer about return types or dead branches of the code should vanish.

Dead code branches

It turns out that the private Avrora.Config modules were too optimized which caused the dialyzer to report dead branches inside the code which was using if/else conditions with that config. The solution was to make it a bit more dynamic, but with a constant access time.

Return type mismatch

Another problem was the private Avrora.Schema return type, which was mismatching for every private client. So now, all private clients will use the only one schema type Avrora.Schema, all the functionality was removed from this module and it became just a struct.

Kudos to @LostKobrakai for raising the issue 💙