Cgp-serde: A modular serialization library for Serde powered by CGP

The providers in CGP work a little different than implicit parameters in Scala. Specifically, the provider implementations are bound to a `Context` or `Self` type during compile-time wiring. So if you know the concrete `Context` type, then you can resolve all provider implementations for that context.

Because the wiring is done globally for an explicit `Context` type, there is no issue of ambiguity that arise based on when an implicit parameter is bound. I call this scoped coherence, as it leverages incoherence for overlappable implementations, but still maintain global coherence through the wiring in a context type.