Compile Scala code with Zinc

[jadenPete]

This issue is part of a broader proposal to merge some of the features in lucidsoftware/rules_scala into this ruleset.

The tracking issue for this effort

The relevant proposal sections:

• {Zinc, Correct} – Choose Two
• Zinc's Compiler Interface

Note that we're not interested in pursuing incremental compilation; rather, we're interested in everything else Zinc has to offer.

A few of the benefits we would get by invoking the compiler via Zinc:

• We can invoke the compiler programmtically via the compiler interface
  • This would prevent us from having to spin up a separate JVM for each compiler invocation
  • This would allow us to invoke the Scala 2 and Scala 3 compiler via the same API
• Zinc outputs an analysis file that includes information about classes, methods, which dependencies were used, etc.
  • This could be used for dependency checking, test discovery, main method detection, etc.

See the proposal for more information.