Hibernate: Auto detect CockroachDB dialect

[vy-ton]

Looks like Hibernate supports a way to auto-detect the right dialect. This provides better UX than requiring users to set the hibernate.dialect property, especially since CockroachDB has different dialects for different versions.

[rafiss]

The Hibernate code does this by inspecting the protocol metadata, which we report as Postgres 9.5

Will follow up in the Hibernate project to ask if they have a suggestion for how we could check the CockroachDB version.