Introduce Group model to Mautic's access control

[rcheesley]

I think you’re referring to this:

Implement roles (in addition to access levels) for users

Combination of two GH issues: Grouping Users by role, so they are able to share content · Issue #6162 · mautic/mautic · GitHub and Add User Groups for more granular Permission Controls... · Issue #6642 · mautic/mautic · GitHub Add User Group(s) option to allow for more granular Permissions Controls for Mautic instances that have multiple users operating multiple campaigns. I just discovered this need, I think, unless there’s a way to go about this that I am unaware of. So let’s use a Universit…