Location backend permissions and issues

**Question 1:** Basically there are four possible options for location permission for apps:

- always allow
- allow only when using the app
- always ask
- block

Do the NLP location backends require "always allow" to work, or is it enough to give them "allow only when using the app"?
I'm having similar problems as #198 when I use the "My Location" app from F-droid - only few if any backends are showing any location despite being enabled and configured. GPS still works... but getting a lock might take time.

If "always allow" is required, it would be useful if microG hinted the user to give this permission. Not all backends ask for it automatically.

**Question 2:** What actually happens/should happen when a backend is disabled in microG settings? I disabled one backend (Wifi location service) but when I use the "My Location" app, it may still show location from this backend, and a location request from this backend is also logged in permissions settings.

**Question 3:** My Location app shows three categories: GPS, Network and UnifiedNLP Backends. What is "Network" backend here?

**Question 4:** When location is disabled from phone settings (e.g. by clicking the location button in the top bar in the main screen), does this also disable all UnifiedNLP backends? If an app asks for location, what does it get?

**System information:**
Using LineageOS 18.1 for microG, last updated 7th of October. I have the following backends installed:
- Apple Wifi (org.microg.nlp.backend.apple)
- Deja Vu location service (org.fitchfamily.android.dejavu)
- GSM Location service (org.fitchfamily.android.gsmlocation)
- GSMNetworkLocationProvider (org.gfd.gsmlocation)
- Mozilla Location Service (org.microg.nlp.backend.ichnaea)
- Radiocells.org Unified Network Location Provider Backend (org.openmap.unifiedNlp)
- Wifi location service (org.fitchfamily.android.wifi_backend)

Start by reproducing the four reported questions with the My Location app on LineageOS 18.1 for microG, using the listed UnifiedNLP backends and Android location settings. Trace permission handling, backend enable/disable behavior, and the distinction between Network and UnifiedNLP Backends; done requires an agreed behavior or documentation for each case.

Written by the indexing model from the issue text.