- Add handling for enum, anyOf, and oneOf
- So long as the order of normalizers is maintained, no handling for
  const is necessary
- Add additional tests

- Update log message
- Support schema.const in case transforms are reordered in the future

- Apply new prettier styles

- Introduce warning() to output console warnings
- Add warning for nullable const, where const value is not null
- Move nullable transform before const->enum transform so that potential
  warning about nullable const can display
- Remove anyOf and oneOf handling since JSON spec should only constrain
  possibilities, not expand (allowance made for enum and const to expand
  types but they show warnings when this happens).
- Avoid pushing 'null' onto available types if it already exists.