[Draft] Extract Connect SDK from sources

[Phanatic]

This PR does a few major refactors to the airbyte-source, mainly:

1. Extract out all code that connects to PlanetScale's sync service into a separate repository.
2. Adopt the same pattern as planetscale/fivetran-source to generate schema and serialize results.
3. Remove all PlanetScale Sync specific code from this repository and reference the common sdk at planetscale/connect-sdk

Follow-up

1. See if we can move some of the common serialization hints such as enums, sets and spatial types to common library.