Support scanning group folders

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Is your feature request related to a problem? Please describe.
Me and my wife use Nextcloud in combinatio with the app to automatically back up our photos from our phone. I've set up a group folder with https://apps.nextcloud.com/apps/groupfolders so that our photos are uploaded to the same folder which we can both access. This helps keep all our photos in one place.

Describe the solution you'd like
Currently the maps app doesn't scan these gorup folders, it only scans user folders. It would be nice if there was some sort of configuration to add custom paths, or the support the groupfolders app in some way.

Describe alternatives you've considered
I haven't really considered alternatives. I guess our setup is based on some personal preferences of wanting our photos in one place. I don't think there are equally powerful map apps for nextcloud either.

Additional context
N/A?

No files, tests, or entry points are named. Start by locating the Maps app's photo-scanning flow and checking how the groupfolders app exposes shared paths; define the supported configuration or integration and verify that photos in a group folder are indexed without breaking user-folder scans.