Fixes / improvements on CtsSettingsDeviceOwnerApp.

- Added self_disable option on receivers so they can be manually
  unset when the test case fails.
- Improved logging.
- Replaced some JUnit assertions with Truth's.
- Added support to headless system user mode (by installing DO on
  user 0 and running tests on current user).

These tests are still failing on automotive, but because the
CarSettings doesn't show the expected UI (before they were not even
running).

Bug: 182409057

Test: adb shell am broadcast --user cur -a disable_self 'com.google.android.cts.deviceowner/.DeviceOwnerTest\$BasicAdminReceiver'
Test: atest com.google.android.cts.settings.PrivacyDeviceOwnerTest # on phones and automotive

Change-Id: Ia1605d56c83c002afaf7b930e585efa5669e686b
6 files changed