Add admin dashboard or cli

[AidanTilgner]

This doesn't need to be anything fancy, but we do need some way of managing users, roles, etc. This could be as simple as a cli to start out, since the goal is mostly to be an mvp template. That being said, given the nature of the application, making an actual website page would probably be better.

[AidanTilgner]

Added a /admin/users route visible to admins and superadmins