Implement work-profile infra in BasePreferenceController

- Add settings:forWork in xml
- Set mIsForWork based on xml attribute
- Delete WorkProfilePreferenceController and move its function to
BasePreferenceController

Fixes: 123376083
Test: Add work profile, go to Settings->System->Language&input,
UI should show work profile related items
Change-Id: Id2dcbb0e158c117cdfd363466a275f4e133c345e

tests/robotests/src/com/android/settings/location/LocationForWorkPreferenceControllerTest.java

@@ -15,8 +15,6 @@
  */
 package com.android.settings.location;
 
-import static com.google.common.truth.Truth.assertThat;
-
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.doReturn;
@@ -114,17 +112,6 @@ public class LocationForWorkPreferenceControllerTest {
         verify(mPreference).setSummary(R.string.switch_off_text);
     }
 
-    @Test
-    public void isAvailable_noManagedProfile_shouldReturnFalse() {
-        when(mUserManager.getUserProfiles()).thenReturn(new ArrayList<>());
-        assertThat(mController.isAvailable()).isFalse();
-    }
-
-    @Test
-    public void isAvailable_hasManagedProfile_shouldReturnTrue() {
-        assertThat(mController.isAvailable()).isTrue();
-    }
-
     @Test
     public void onLocationModeChanged_disabledByAdmin_shouldDisablePreference() {
         mController.displayPreference(mScreen);