Add admin functionalities

[AlbertoPdRF]

Is your feature request related to a problem? Please describe.

There's the infrastructure for an admin dashboard in place, but there's nothing on it.

Describe the solution you'd like

I'd like that we start to fill the dashboard with some necessary functionality, which could go from displaying metrics (it probably could integrate #23) to moderate the app's content. It still needs to be decided how it will look like and what does it exactly need to include, but I'm opening the issue now to not lose track of it.

Describe alternatives you've considered

Keep the dashboard empty.

Additional context

None at the moment.