Follow-up improvements to zen mode icon picker

* Propose icons from com.android.internal.R instead of android.R (as a proof of concept) since this is what we'll be doing with the final icons.
* Provide the icon options as a parameter to the controller (can also be used for testing).
* Fix some Lint warnings.

Test: atest ZenModeIconPickerListPreferenceControllerTest
Bug: 333901673
Flag: android.app.modes_ui
Change-Id: I023eed0fd5719c5c4540f8d145335f60d088e7fb

src/com/android/settings/notification/modes/ZenModeActionsPreferenceController.java

@@ -31,8 +31,6 @@ import com.android.settingslib.widget.ActionButtonsPreference;
 
 class ZenModeActionsPreferenceController extends AbstractZenModePreferenceController {
 
-    private ActionButtonsPreference mPreference;
-
     ZenModeActionsPreferenceController(@NonNull Context context, @NonNull String key,
             @Nullable ZenModesBackend backend) {
         super(context, key, backend);