Add log/trace for case where plugin stop command times out

We have seen some intermittent failures in the new "testDashboardStopExternalServer" tests for the new "stop" function using LMP/LGP to stop a session not started by LTE.

It'd be nice to have some logging to go along with this failure. Do we see something problematic or is nothing at all even running in this process?

My naive attempt to add this: https://github.com/scottkurz/liberty-tools-eclipse/commit/5b331362be06621e73b4da34d19c0bcc39a6a197 doesn't really work. Unfortunately the IO read might end up blocking and preventing the Job's run() method from ever returning.

It seems the IO would have be done differently, on another thread and/or another library.

(Note the test output would still be kind of weird in that the process' output streams are all smashed together.. regardless of this one change idea.)

Start by running or reading the testDashboardStopExternalServer tests and the new stop function, then review the attempted logging change in commit 5b331362be06621e73b4da34d19c0bcc39a6a197. Done means timeout diagnostics are captured without blocking the Job's run() method, with the intermittent failure providing useful process output.