Suggestion: Automatically switch theme of Mozilla Firefox

Firefox stores profile data in /home//.mozilla/firefox/profiles.ini
Or Whatever directory is listed here: about:profiles

Data of profiles.ini looks like this
```
[General]
StartWithLastProfile=1

[Profile0]
Name=dev-edition-default
IsRelative=1
Path=0xo36fmu.dev-edition-default

[Profile1]
Name=default
IsRelative=1
Path=xngzkevy.default
Default=1
```

I don't yet know if this has anything to do with light and dark themes but I am looking into this.

Thanks.

Start by inspecting the Firefox profile data at /home//.mozilla/firefox/profiles.ini, or the directory listed by about:profiles. Determine whether these settings expose light and dark theme selection; done means Firefox changes themes automatically with the application's desktop theme, with a reproducible check for the supported profile setup.

Written by the indexing model from the issue text.