* Move CLI to TransportSqlAction
* Moves REST endpoint from `/_cli` to `/_sql/cli`
* Removes the special purpose CLI transport action instead
implements the CLI entirely on the REST layer, delegating
all SQL stuff to the same action that backs the `/_sql` REST
API.
* Reworks "embedded testing mode" to use a `FilterClient` to
bounce capture the sql transport action and execute in embedded.
* Switches CLI formatting from consuming the entire response
to consuming just the first page of the response and returning
a `cursor` that can be used to read the next page. That read is
not yet implemented.
* Switch CLI formatting from the consuming the `RowSetCursor` to
consuming the `SqlResponse` object.
* Adds tests for CLI formatting.
* Support next page in the cli
* Rename cli's CommandRequest/CommandResponse to
QueryInitRequest/QueryInitResponse to line up with jdbc
* Implement QueryPageRequest/QueryPageResponse in cli
* Use `byte[]` to represent the cursor in the cli. Those bytes
mean something, but only to the server. The only reasonint that
the client does about them is "if length == 0 then there isn't a
next page."
* Pull common code from jdbc's QueryInitRequest, QueryPageRequest,
QueryInitResponse, and QueryPageResponse into the shared-proto
project
* By implication this switches jdbc's QueryPageRequest to using
the same cursor implementation as the cli
Original commit: elastic/x-pack-elasticsearch@193586f1ee
5d3f5cc4f8