transformer: standalone cli

[Boshen]

• rework the options architecture so they don't duplicate across napi, cli and the transformer itself.

The same architecture also applies to the minifier.

[Boshen]

I'm not going to have the bandwidth to work on this in the next couple of weeks :-(

[tylersayshi]

Is it something that would be approachable for a new contributor? If not, I'll look for something else :)