Missing progress indicator while adding offline layers with "don't keep activities"

[dbemke]

ODK Collect version

the master version 7d30e18

Android version

10, 14

Device used

Redmi 9T, Pixel 7a

Problem description

The progress indicator is missing while adding offline layers if there's the "don't keep activities" setting enabled. For a moment it looks as if the list of offline layers to add is empty (especially if there are many offline layers to add).

Steps to reproduce the problem

1. Set "don’t keep activities” in the device.
2. Go to any form with maps and open the map.
3. Tap the offline layers icon, "add layers” and select some layers to add.
4. While on "Add layers” check the list of layers to add and the progress indicator.

Expected behavior

The progress indicator should appear.

Notes

It looks like this is because we use one LiveData to represent "loading" for OfflineMapLayersViewModel and when the Activity is recreated loadExistingLayers finishes quickly and sets isLoading to false. We can either split out two progress states, or use TrackableWorker and modify it to count work in progress rather just being on/off.