Allow Dart to query realtime tasks

[adarshsanjeev]

Add the ability for Dart to query real-time tasks.

Most of the changes are around including the realtime segments while slicing the inputs in the controller. There are also some small changes around handling worker counts in the case of no historical segments.

Additionally, cloneQueryMode is now respected by Dart.

Release Notes

• MSQ Dart is now able to query real-time tasks by setting the query context parameter includeSegmentSource to realtime, in a similar way to MSQ tasks. Dart queries real-time tasks by default.

---

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.
• a release note entry in the PR description.
• 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.

[gianm]

Generally looking good. I don't see an IT - did you test it to make sure it works?

Btw, I don't think we have Dart integration tests yet, so I won't ask you to add an IT in this patch, but we should address that in the future.

[adarshsanjeev]

Generally looking good. I don't see an IT - did you test it to make sure it works?

Yes, I have tested it locally, with only real-time segments as well as a mix.

I too noticed that there isn't a Dart IT. I will add one in another PR.

[gianm]

To mirror the suggestion for IndexerControllerContext, consider moving this to a constant in DartControllerContext.

[adarshsanjeev]

Changed! This one instance should probably remain as REALTIME, not a default value. This part of the code is common to both and should only be called if realtime segments are queried.