Previously, a JVM that was forked by spring-boot:run could be orphaned
when the parent process (the Maven build) was terminated in an IDE. Note
that this doesn’t happen when spring-boot:run is invoked from a shell.
This commits add a shutdown hook that registered when RunMojo forks the
JVM. The shutdown hook attempts to kill the forked JVM’s RunProcess
rather than relying on the death of the parent process being sufficient
to also kill the child.
Closes gh-5815
310be23ad5