Enhancement for configurable automatic dump upon thread exhaustion

[aogburn]

For some scenarios, reaching thread pool exhaustion can be a critical state always requiring thread dumps for an RCA. So it would be helpful for the executor to have a configurable option allowing an automatic dump upon thread exhaustion.

[franz1981]

jboss-threads/src/main/java/org/jboss/threads/EnhancedQueueExecutor.java

Line 1797 in f9dc973

if (UPDATE_STATISTICS) rejectedTaskCounter.increment();

this seems to suggest we just send a RejectedEx while would be great to have a rethrow as OOM somewhere, because OOM due to native thread exhaustion won't make the JVM to die if configured with ExitOnOOM, see https://bugs.openjdk.org/browse/JDK-8155004