Re-enable IdleStateMonitor

[pihme]

This commit re-enables IdleStateMonitor and fixes it to make it usable.

Learnings:

• we need to be mindful of multi-threading
• the sequence of events is not always intuitive. E.g. when the stream processor is writing the follow-up events, then the listener calls for the new log entries and the skipped entries can come in before the stream processor finished writing all events.
• Because of that, the old mechanism detected an idle state prematurely, i.e. after the first follow-up event was written to the log and immediately skipped by the record stream processor. It didn't wait whether more follow-up events are to come
• Therefore, there is now a timer started when the first idle state is detected.
• The timer delay may depend on the speed of the machine. So maybe we need to tune this going forward.

Related issues

closes #6
closes #71
closes #77

Definition of Done

Not all items need to be done depending on the issue and the pull request.

Code changes:

• The changes are backwards compatibility with previous versions
• If it fixes a bug then PRs are created to backport the fix

Testing:

• There are unit/integration tests that verify all acceptance criterias of the issue
• New tests are written to ensure backwards compatibility with further versions
• The behavior is tested manually

Documentation:

• Javadoc has been written
• The documentation is updated

[remcowesterhoud]

@pihme Great job getting this working 🏆

I have a few minor comments, please have a look at them and feel free to merge it after!

[pihme]

@remcowesterhoud Responded to your comments. Please have another look and close any conversations you feel are resolved, then let's discuss the remaining ones.