Support Cockroach DB

[tobiasschaefer]

Cockroach DB can be used with the PostgreSQL Driver which makes it very easy to use: https://www.cockroachlabs.com/docs/stable/postgresql-compatibility.html

However, I stumbled across some changes added recently in the Spring Integration for CockroachDB:

• https://github.com/camunda/camunda-bpm-platform/blob/master/engine-spring/core/src/main/java/org/camunda/bpm/engine/spring/SpringTransactionsProcessEngineConfiguration.java#L78
• https://github.com/camunda/camunda-bpm-platform/blob/master/engine-spring/core/src/main/java/org/camunda/bpm/engine/spring/SpringTransactionInterceptor.java#L76
  (look at the history of the Spring Engine)

Todo:

• add missing interceptor, fix exception handling. Anything else missing?
• test it - > document how to test, preferably with TestContainers or Docker
• document how to use it in README (if not same as PostgreSQL)

FYI:

• https://www.cockroachlabs.com/docs/stable/cockroachdb-in-comparison.html
• https://www.cockroachlabs.com/docs/stable/start-a-local-cluster-in-docker-mac.html
• https://vladmihalcea.com/how-to-get-started-with-cockroachdb/