feat(api): support selectors in window function order_by and group_by

[cpcloud]

Support selectors in window function group_by and order_by arguments. Closes #9637.

[kszucs]

I would prefer not to move the base selector class to ibis.common since it is tied to ir.Table.
I think Selectors could be viewed as another kind of deferred (or rather Resolver) producing a sequence of outputs and deferreds are decoupled from the ir.

[kszucs]

If I recall correctly even bind() would properly handle that, so refactoring selectors as Resolvers could simplify the codebase, but that should be done in a separate PR.

[cpcloud]

I moved the class to avoid an import cycle and having it anywhere else didn't really fit.

If you have another suggestion that isn't to refactor the whole class :) I'm happy to hear it!

[kszucs]

Ohh, I wasn't aware of the import cycle.

[cpcloud]

Since there's a bit of noise from dealing with the import cycle from using Selector at the top level of builders.py, I'm calling out that this is the change that enables use of a Selector in the group_by and order_by window APIs.

We're already calling Table.bind on these two fields in the appropriate place, we simply needed to allow them in the signature of this builder to allow them to get passed through the API.