Support Union of `Enum` and/or `Literal` in annotations for `with_annotated` decorator

[neoniobium]

Feature Request

Support Union of Enum and/or Literal in annotations for with_annotated decorator. Especially unions for different Enums seams to be desirable to reduce code duplication.

Code Example

class App(Cmd):

    @with_annotated
    def do_something_with_enums(a: EnumA, b: EnumB, combine: EnumA | EnumB) -> None:
        ...

[KelvinChung2000]

I will add support for this use case. For now, I will allow only a mix of Enum and Literal, since they are "constant-like". For most other options, I think it will be very ambiguous to tell what it should resolve to.