Dart resource deprecation

[adarshsanjeev]

Presently, DartResources handles DART queries, while SqlResource handles sql native queries. This includes some Dart specific code which needs to be run for creating and cancelling queries.

This PR aims to unify these interfaces by adding an "engine selector" to SqlResource to allow it to run native as well as Dart queries. This involves pushing any engine specific code into the SqlEngine and refactoring the Dart cancellation to be more generic.

Release Notes

• Dart specific endpoints have been removed and folded into SqlResource.
• Added a new engine QueryContext parameter. The value can be native or msq-dart. The value determines the engine used to run the query. The default value is native.

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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.

[kgyrtkirk]

I know you've just opened to run CI; but I wonder if this should be the path or not

[kgyrtkirk]

looks good! left a bunch of comments but nothing really serious... mostly just questions/minor notices :)