Add opacity settings to on-screen controls (#798)

* Restore resize controls, Make buttons oval

* Create new default configuration

* Split Configuration Mode into separate Move and Resize modes

* Add transparency setting for on-screen buttons

* Updated translations for on-screen controls

Co-authored-by: Leo <chun.huang@student.manchester.ac.uk>

app/src/main/res/values-nl/strings.xml

@@ -125,5 +125,6 @@
   <string name="category_advanced_settings">Geavanceerde Instellingen</string>
   <string name="title_video_format">Verander H.265 instellingen</string>
   <string name="summary_video_format">H.265 verlaagt video bandbreedte vereisten maar benodigdt een recent apparaat.</string>
+    <string name="suffix_osc_opacity">%</string>
 
 </resources>