Handle file drop from input_manager

A file is pushed (or an apk is installed) to the device on file drop.
This behavior is specific to the screen and its input_manager.

app/src/screen.h

@@ -70,6 +70,7 @@ struct sc_screen {
 
 struct sc_screen_params {
     struct sc_controller *controller;
+    struct sc_file_pusher *fp;
     struct sc_key_processor *kp;
     struct sc_mouse_processor *mp;