add config changes to MainActivity and re-instate notification manager (I think this should fix starting crash while avoiding the resizing bug)

src/android/app/src/main/AndroidManifest.xml

@@ -75,6 +75,7 @@
 
         <activity
             android:name="org.citra.citra_emu.ui.main.MainActivity"
+            android:configChanges="density|orientation|screenSize|keyboard|keyboardHidden|uiMode"
             android:exported="true"
             android:resizeableActivity="false"
             android:screenOrientation="landscape"

src/android/app/src/main/java/org/citra/citra_emu/CitraApplication.java

@@ -65,8 +65,8 @@ public class CitraApplication extends Application {
         }
 
         NativeLibrary.LogDeviceInfo();
-        // TODO (amwatsonn) Disabled because this triggers a bug on Quest.
-        //createNotificationChannel();
+
+        createNotificationChannel();
 
         databaseHelper = new GameDatabase(this);
     }