Make it less verbose to construct multi-controlled Bloqs.

[tanujkhattar]

bloq.controlled() gives a controlled version of a Bloq with a single control wire added. Another very common use-case is to construct a controlled version of a Bloq with n controls. Right now, the way to achieve that is bloq.controlled(CtrlSpec(cvs=[1]*num_controls)).

This feature request is to make the latter use case less verbose for users. For example, maybe bloq.controlled(num_controls) or, at the very least, something like bloq.controlled(CtrlSpec(num_controls=num_controls))

cc @mpharrigan

[mpharrigan]

Yes, I think having a variant of CtrlSpec that supports just a number of controls would be a good extension. Whether we should provide syntactic sugar via the Bloq.controlled() method is up for debate. I'd say start with no sugar, and evaluate whether to add it in later.