Condition that checks for a solo tag

Feature Request placed on behalf of this client: Olivia Regan

Client would like a way to create a contact group of contacts that have one tag and no other tags. 

Usecase: Client has a lot of tags in their account and would like to be able to isolate contacts based off of having one tag, but no other tags instead of creating a plethora of conditions for all of the tags the contact should not have.

Please note: An alternative solution was provided to the client.