Permission requests cleanup in hotspot test app

The hotspot test app currently asks for permissions once when it starts and then just refuses to work if they were not granted. We should probably introduce some sort of PermissionController that encapsulates all that logic and ensures that the necessary permissions and enabled system settings (wi-fi, location) are requested properly.

Subtask of #1081 (closed)

changed milestone to %Install via Bluetooth or Wi-Fi

added Sponsor 6 T: task labels

added S: in progress label

mentioned in merge request hotspot!8 (merged)

added S: in code review label and removed S: in progress label

closed with merge request hotspot!8 (merged)

mentioned in commit hotspot@c5f12d4f

removed S: in code review label

added R: fixed label

changed due date to July 31, 2021