Configure replica settings in sql-server's `config.yaml`

To configure a Dolt sql-server as a MySQL replica, you currently need to log into the SQL shell and run the `CHANGE REPLICATION SOURCE TO ...` statement ([MySQL docs](https://dev.mysql.com/doc/refman/8.4/en/change-replication-source-to.html)) with the desired configuration options. It would be convenient for Dolt customers to be able to set this configuration in the standard `config.yaml` file used by a Dolt sql-server.