chore(developer): improve kmc validation and corresponding tests

* Add a bunch of tests for keys
* Add tests for version. (improves meta test coverage to 100%)
* A bit more consistency cleanup also of error message functions.
* Adds a compiler failure (FATAL) if compile fails after validate
  passes.
* Overall test coverage now 93.5% lines. Biggest gap still kmx-builder.
  All compiler units are >90%.