Implement a CDC connector for Vitess

Hi,
 
We at Bolt (https://bolt.eu/) have implemented a Debezium Development Framework based connector for Vitess (https://vitess.io/).
Vitess is a horizontally scalable MySQL cluster that has built-in sharding support. It uses VStream (https://vitess.io/docs/concepts/vstream/) to feed CDC processes.
 
The Vitess Connector has a similar structure as the Debezium Postgres Connector and reuses many common components, such as `BaseSourceTask`, `ChangeEventSourceCoordinator`, `StreamingChangeEventSource`, etc.
It also provides similar configurations and JMX metrics.
 
This ticket attempts to open-source the Vitess Connector under the Debezium umbrella as an incubating connector.