Validate that registered args begin with dashes, as appropriate.

Otherwise we get a cryptic error further along.

Testing Done:
CI baking. Verified that bad registration triggers these validation checks.

Reviewed at https://rbcommons.com/s/twitter/r/1211/
Migrate more tasks, including all android tasks, to new options.

Renamed --vm-options to --jvm-options, for uniformity.

Testing Done:
Manual testing.

CI baking.

Reviewed at https://rbcommons.com/s/twitter/r/1214/
Sync of https://github.com/pantsbuild/pants/commit/71200ed5fee471bb32c0d77c3535e2a18fd89377