Minor fixes on DeviceAdminAdd controllers:

- Added getRealAvailabilityStatus()
- Fixed DeviceAdminAddSupportController when there is no message.
- Fixed DeviceAdminAddExplanationController on profile / device owner.

Test: atest CarSettingsUnitTests:DeviceAdminAddPoliciesPreferenceControllerTest CarSettingsUnitTests:DeviceAdminAddExplanationPreferenceControllerTest CarSettingsUnitTests:DeviceAdminAddSupportPreferenceControllerTest
Bug: 188585303

Change-Id: Ic8689a69815eea7028f6512731df505ac6235ce2
6 files changed