Supporting dark mode in SuspendedAppActivity

Test: Manual:
1. Suspend an app via 'adb shell pm suspend <package-name>
2. Tap the suspended app's icon.
3. Repeat steps 1 and 2 after enabling dark mode.

Bug: 129397023

Change-Id: If753fcaa2584ec474183de319c66ce7a68ff4e17
Merged-In: I65b38b76eb2f00cc42d644f51e5c4a704af7c2c7