This changes JDBC so it can be released. It bundles the
`sql-shared-client` and `sql-proto` jars into the jar for the jdbc client.
It also Generates a pom for the jdbc driver when you run `gradle assemble`
on it. This will allow us to release the jdbc driver.
It also adds a zip distribution of the jdbc driver with all of its
dependencies bundled in the zip. It'd be nice to bundle all of the jdbc
driver's dependencies in the jar but we can't quite do that yet. So, for
now, to help folks using BI tools use the JDBC driver, we build a zip.
Original commit: elastic/x-pack-elasticsearch@9c668231d4
76c764b379