Publish OpenWhisk artifacts to Maven

To simplify consuming OpenWhisk artifacts in downstream projects we should publish the generated artifcats like common, controller, test jars to Maven repo (both in spanshot form and released artifacts)

This would enable downstream projects to directly consume precompiled jars for there tests instead of building them again as part of build.

This is also needed to support #4525 for publishing Standalone OpenWhisk to maven.

For this to work we should move to Gradle 5.5. first (see #4567)