Add ShutdownHook to cleanup FileLocks on graceful JVM shutdown

Add ShutdownHook to cleanup FileLocks on graceful JVM shutdown

This should avoid stale lock files if the JVM is terminated gracefully.

Implement a ShutdownHook which can register/unregister listeners which
need to do some cleanup during graceful JVM shutdown. This hook is
registered as a Java shutdown hook and  when the JVM shuts down
calls #onShutdown of registered listeners using a parallel stream
to let them run concurrently.

See https://docs.oracle.com/javase/8/docs/technotes/guides/lang/hook-design.html

Bug: 582379
Change-Id: I1621dc5f7d9a8c832b6d1b74cbc47578b1c2f0b8