Add test for Apertis update manager error conditions
Add test to check proper behavior in the following circumstances:
- Power cut during an update
- USB mass storage unplug during an update
- The disk is full during an update
Signed-off-by: Denis Pynkin denis.pynkin@collabora.com Signed-off-by: Frédéric Dalleau frederic.dalleau@collabora.com