SpringApplicationLifecycle provides basic lifecycle operations on the
current Spring Boot application (that is checking if the application has
fully started and gracefully terminate the app). It can be registered as
an MBean of the platform MBean server if a specific property is set.

The Maven plugin uses that MBean to check that the application is ready
before ending the "start" phase. It uses it to trigger a proper shutdown
of the application during the "stop" phase.

If the process has to be forked, the platform MBean server is exposed on
a configurable port so that the maven plugin can connect to it.

Such change permits the maven plugin to integrate a classical integration
test scenario where the "start" goal is invoked during the
pre-integration phase and the "stop" goal during the post-integration
phase.

Closes gh-2525