Schema support

[hariso]

Feature description

Adds support for schemas in Conduit. The work is split as in the lists below. It would be good if we start with #1561 and the conduit-commons issues (minus schema auto-generation) so we can parallelize the rest of the work.

Conduit

• [x] #1561
• [x] #1562
• [ ] #1563
• [ ] #1653
• [ ] #1660

conduit-commons

• [x] https://github.com/ConduitIO/conduit-commons/issues/50
• [ ] https://github.com/ConduitIO/conduit-commons/issues/52
• [ ] https://github.com/ConduitIO/conduit-commons/issues/53
• [ ] https://github.com/ConduitIO/conduit-commons/issues/51

Connector SDK

• [ ] https://github.com/ConduitIO/conduit-connector-sdk/issues/132
• [ ] https://github.com/ConduitIO/conduit-connector-sdk/issues/137
• [ ] https://github.com/ConduitIO/conduit-connector-sdk/issues/138

Processor SDK

• [ ] https://github.com/ConduitIO/conduit-processor-sdk/issues/45

[lovromazgon]

A lot, if not all of the code, needed for auto-generating Avro schemas can be found here.

The utilities mentioned in both SDKs can be placed in conduit-commons, so we can re-use it.