Android: Add theme mode switcher

Similar to app themes, theme modes have to be loaded before directory initialization is ready. So we save the proper key the same way.

Source/Android/app/build.gradle

@@ -96,7 +96,7 @@ android {
 dependencies {
     coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.1.5'
 
-    implementation 'androidx.appcompat:appcompat:1.5.0'
+    implementation 'androidx.appcompat:appcompat:1.5.1'
     implementation 'androidx.exifinterface:exifinterface:1.3.3'
     implementation 'androidx.cardview:cardview:1.0.0'
     implementation 'androidx.recyclerview:recyclerview:1.2.1'