Move ZenModesBackend to SettingsLib.

This will allow us to access it from SystemUI.

Bug: 346519570
Test: builds
Flag: EXEMPT trivial refactor
Change-Id: I5bc480bd4eb0cbf8a26989dd11c064e66e5ee70e

src/com/android/settings/homepage/contextualcards/conditional/DndConditionCardController.java

@@ -105,7 +105,8 @@ public class DndConditionCardController implements ConditionalCardController {
                         + mAppContext.getText(R.string.condition_zen_title))
                 .setTitleText(mAppContext.getText(R.string.condition_zen_title).toString())
                 .setSummaryText(getSummary())
-                .setIconDrawable(mAppContext.getDrawable(R.drawable.ic_do_not_disturb_on_24dp))
+                .setIconDrawable(mAppContext.getDrawable(
+                        com.android.settingslib.R.drawable.ic_do_not_disturb_on_24dp))
                 .setViewType(ConditionContextualCardRenderer.VIEW_TYPE_HALF_WIDTH)
                 .build();
     }