Worker level task metrics

[zachjsh]

Added a new monitor, WorkerTaskCountStatsMonitor, that allows each middle manage worker to report metrics for successful / failed tasks, and task slot usage. There is an exsiting TaskCountStatsMonitor, which allows for reporting of task metrics but is done so by the overlord and so task metric data for individual workers is lost, hence this monitor. This monitor is only supported on MiddleManager type NodeRole.

Also fixes an inconsistency in the name of the existing task metric for tracking taskslot usage.

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[jon-wei]

vesion -> version

[zachjsh]

ahhh dang lol. Good catch

[zachjsh]

Fixed