Gui: Direct Draw API (#2215)

* Furi: allow on-fly thread priority change. Gui: Direct Draw API. DirectDraw debug app.
* Gui: drop input in direct draw
* Furi: handle priority change for starting threads
* DirectDraw: rollback to FreeRTOS primitives for priority change

applications/services/gui/gui_i.h

@@ -62,6 +62,7 @@ struct Gui {
 
     // Layers and Canvas
     bool lockdown;
+    bool direct_draw;
     ViewPortArray_t layers[GuiLayerMAX];
     Canvas* canvas;
     CanvasCallbackPairArray_t canvas_callback_pair;