Reconsider how --module and --type should work

[Avaq]

We might want to unify these two options to simplify the CLI. We might also want to consider that the esm module option could be inferred from the .mjs file extension. Currently inference only works to detect --type.

[danse]

I gave a quick look at this, just to keep a conversation going. At first glance it seems sensible to unify the two. As far as i understand the main areas of intervention are the option definition and validation. Any reason why not to unify the two options?