register OnSharedPreferenceChangeListener in LatinIME.onCreate

because it's unregistered in onDestroy
(registering twice is not an issue)

though maybe not unregistering would be more correct, as it's registered in app.onCreate?

fixes GH-1670

app/src/main/java/helium314/keyboard/latin/LatinIME.java

@@ -626,6 +626,7 @@ public class LatinIME extends InputMethodService implements
 
     @Override
     public void onCreate() {
+        mSettings.startListener();
         KeyboardIconsSet.Companion.getInstance().loadIcons(this);
         mRichImm = RichInputMethodManager.getInstance();
         AudioAndHapticFeedbackManager.init(this);