Java test

[simonz130]

Introducing environment tests to java-logging repo - part 1 - changes only related to env-tests-logging repo.

Includes:

• basic java code to spin up pub/sub subscription, listen for messages and invoke a test based on message name
• scripts to package java code
• tests deriving from common for java use-case

[daniel-sanche]

Closing this in favor of https://github.com/googleapis/env-tests-logging/pull/40