FullscreenUI: Untangle Escape button behaviour

Now it doesn't race against Open Pause Menu

src/frontend-common/imgui_fullscreen.h

@@ -128,14 +128,13 @@ void EndLayout();
 void QueueResetFocus();
 bool ResetFocusHere();
 bool WantsToCloseMenu();
+void ResetCloseMenuIfNeeded();
 
 void PushPrimaryColor();
 void PopPrimaryColor();
 void PushSecondaryColor();
 void PopSecondaryColor();
 
-bool IsCancelButtonPressed();
-
 void DrawWindowTitle(const char* title);
 
 bool BeginFullscreenColumns(const char* title = nullptr);