Make some device info related slices public.

Only PreferenceControllers with isPublicSlice() set to true are exposed
to other apps. Others will be Settings only.

Bug: 141088937
Test: robotests
Change-Id: Id38fd0203a4efc812e30990491786b4d8aff8902

tests/robotests/src/com/android/settings/deviceinfo/BuildNumberPreferenceControllerTest.java

@@ -205,4 +205,9 @@ public class BuildNumberPreferenceControllerTest {
         final CharSequence data = clipboard.getPrimaryClip().getItemAt(0).getText();
         assertThat(data.toString()).isEqualTo(mController.getSummary());
     }
+
+    @Test
+    public void isPublicSlice_returnTrue() {
+        assertThat(mController.isPublicSlice()).isTrue();
+    }
 }