[Feature Request] Extend functionality of reactrestrict: Only allow a certain role to add reaction

[NNTin]

Is your feature request related to a problem? Please describe.
My use case is to create a poll which is publicly visible but only certain people are allowed to cast a vote.
With the current implementation you have to give everyone who is not allowed to vote a role.

Describe the solution you'd like
Instead of just blacklisting a role from reacting, allow us to also whitelist certain roles.
So to create a poll where only users with a certain role are allowed to vote you can use that certain role.