Computational instance for GOV' rule

[UlfNorell]

This doesn't do anything about #212, the existing definition of the rule is computational even without enforcing unique GovActionIds.

Question: This defines any⇔∃ locally with the computational instance, but it feels like something that should either already be in the standard library (where I couldn't find it), or be defined in some more reasonable place in our repo.

[WhatisRT]

I found it, it's Any↔ from Data.List.Membership.Propositional.Properties. However, it's still in the old function hierarchy, so I had to convert it to the new one. That conversion function is exactly the reason why we're not on any released version of the stdlib btw.