Combined extract decorator

[elijahbenizzy]

Is your feature request related to a problem? Please describe.
We have two separate codepaths for extract_fields and extract_columns.

Furthermore, extract_fields requires one to write the type in the extract, but we should have that information in the fn output.

I think we can simplify the code quite a bit.

Describe the solution you'd like
A single extract (name TBD) decorator that does the following:

@extract("foo", "bar")
def foo_bar(foo: int, bar: int) -> Dict[str, int]:
    return {"foo": foo, "bar": bar}

@extract("foo", "bar")
def foo_bar(foo: pd.Series, bar: pd.Series) -> pd.DataFrame:
    return pd.DataFrame({"foo": foo, "bar": bar})

Then it can register "extensions" to allow for us to processing different extractions. E.G. different DF types, etc...

If its a Dict[str, foo], we know it'll be a bunch of foo type outputs. If its a pd.DataFrame we know its going to be pd.Series. Etc...

Describe alternatives you've considered
Not doing this.

Additional context
Just an idea that popped up when writing some new features.