Add read-only permission for /api/v3/rbac/permissions/users

[matthias-bruhse]

Is your feature request related to a problem? Please describe.
We have an automated, regular check that compares our Terraform IaC configuration against the actual state of the Authentik setup. The user for this has exclusively read-only permissions to the API. As far as I can tell, accessing /api/v3/rbac/permissions/users is not possible without super user privileges.

Describe the solution you'd like
Add a permission that allows GET on /api/v3/rbac/permissions/users without requiring super-user privileges or any other write permissions.

Describe alternatives you've considered
Elevating privileges is out of the question.