Adds support for the PP shaders in the Android UI.

Copies over the PP shaders to the APK's assets and installs them on run.
Exposes them via the video settings UI.

This is in anticipation of dropping the workaround for rotated blits on Adreno and instead forcing shader usage by the user.

Source/Android/res/xml/video_prefs.xml

@@ -28,6 +28,11 @@
             android:summary="@string/anisotropic_filtering_descrip"
             android:title="@string/anisotropic_filtering"/>
 
+        <ListPreference
+            android:key="postProcessingShader"
+            android:summary="@string/postprocessing_shader_descrip"
+            android:title="@string/postprocessing_shader"/>
+
         <CheckBoxPreference
             android:defaultValue="true"
             android:key="scaledEFBCopy"