Support for a permission in ability file for "invited to anything as :role"

The idea here is that sometimes you want to grant permissions on entity A for any user that is invited to an unrelated entity B in a specific role:

Given BirdBank and Campus exist as entities, and Campus accepts invitation as :campus_manager

```
can :manage, BirdBank, roles[any(:campus_manager)]
```

Would need to implement the any() method to accomplish this.
