Vitess connector should expose vstream flags

There is a VStream flag stop_on_reshard in Vitess: https://github.com/vitessio/vitess/blob/016756e339ad052b63d238ef87eb177f79a8c18d/go/vt/vtgate/vstream_manager.go#L81-L84

It controls if the old VStream will be stopped on reshard operation. If this is true, say we are reshard A into B and C, the stream on shard A will be stopped. When this is false (the default), the same stream will try to read from shard B and C automatically.

I think with kafka connect, we should provide the option to the client and decide what is the desired behavior