Decouple route authorization and layout

[jescalada]

Is your feature request related to a problem? Please describe.
Related to #9. Currently, the UI's /admin/* routes are the default base route for every route (for logged-in users). We want to change that to /dashboard/* and then keep the actual admin routes under /dashboard/admin/*.

Describe the solution you'd like
This will require modifying the various frontend routing files and all the tests that rely on the current route naming.

Describe alternatives you've considered
Leaving it as it is would be very confusing.

Additional context
None.