Enhance exception logging in MonitoredJob#handleExceptionSafely

[sleberknight]

MonitoredJob#handleExceptionSafely logs the fact that an exception occurred at WARN level. For a job named "MyJob", the log message looks like:

Encountered exception in job: MyJob

MonitoredJob implements kiwi's CatchingRunnable, which logs the actual exception. But, we should change the message so that it provides information about the exception type, message, and possibly cause and/or root cause so that it can be correlated with the error and exception stack trace logged by CatchingRunnable.

In a recent problem, I was debugging a job that threw an org.kiwiproject.concurrent.AsyncException, which was caused by a java.util.concurrent.ExecutionException, which had a root cause of java.lang.NullPointerException.

Instead of the above error message, it would have been more useful to see a message like:

Encountered org.kiwiproject.concurrent.AsyncException exception in job 'MyJob' with root
cause java.lang.NullPointerException (look for the exception and stack trace logged by
CatchingRunnable#runSafely)

So, this tells you at a glance what the exception and root cause were, and also that you can find the exception information and stack trace that was logged by CatchingRunnable.