Fix PermissionAppsFragmentTest

PermissionAppsFragmentTest is actually a base class of three tests:

- LocationPermissionAppsFragmentTest
- CustomPermissionAppsFragmentTest
- StoragePermissionAppsFragmentTest

So, this impacts all three.

This change does the following:

- Add more helpful exception messages.
- Add verbose timing logs. (We've run into slowness issues with this
  test before, and these logs will help us verify in case we run into it
  again.)
- Ignore Storage and Location tests on R, due to an R-specific bug.
- In some cases these screens don't have a scrollable, and in some cases
  they do. So, if a scrollable doesn't exist, just find the object and
  don't try to scroll for it.

Fix: 296932325
Test: atest --iterations 10 LocationPermissionAppsFragmentTest CustomPermissionAppsFragmentTest StoragePermissionAppsFragmentTest
Change-Id: Ibe31d41d057cc069b726018bc16fe293ce90890a