Too big. Sorry. Some good things though:
1. Share some code between CLI and JDBC. Probably a good thing
at this point, better as we go on, I think.
2. Add round trip tests for all of proto.
3. Remove the `data` member from `QueryInitResponse` and
`QueryPageResponse` so we response serialization is consistent with
everything else.
Original commit: elastic/x-pack-elasticsearch@c6940a32ed