Add alternate map tile providers

F-Droid version of TICE requires manually filling a Mapbox access token, but it's nowhere trivial to get one. Mapbox account registration requires giving out credit card number, which is not great for privacy or accessibility.
Add some other map providers which don't need that.

A quick search brings up this: Leaflet/Leaflet#6336
There's also this example implementation of map viewer with multiple backends: https://osmdroid.github.io/osmdroid/

[Quantum-Future]

Give the option to use OpenStreet Maps please.