gitadora: use native touch for single-window mode (#828)

## Link to GitHub Issue or related Pull Request, if one exists
#814 

## Description of change
Make gitadora arena model use native touch instead of wintouchemu. Only
single window mode with overlay is affected.

This removes the last consumer of `INJECT_MOUSE_AS_WM_TOUCH` so all of
that code can be deleted.

## Testing
Tested touch screen and mouse interaction with single window mode.

src/spice2x/games/gitadora/gitadora.cpp

@@ -11,8 +11,8 @@
 #include "hooks/audio/audio.h"
 #include "hooks/audio/mme.h"
 #include "hooks/graphics/graphics.h"
-#include "misc/wintouchemu.h"
 #include "overlay/overlay.h"
+#include "touch/native/nativetouchhook.h"
 #include "util/cpuutils.h"
 #include "util/deferlog.h"
 #include "util/detour.h"
@@ -653,9 +653,7 @@ namespace games::gitadora {
             // monitor/touch hooks (windowed or full screen)
             if (GRAPHICS_PREVENT_SECONDARY_WINDOWS) {
                 // enable touch hook for subscreen overlay
-                wintouchemu::FORCE = true;
-                wintouchemu::INJECT_MOUSE_AS_WM_TOUCH = true;
-                wintouchemu::hook("GITADORA", avs::game::DLL_INSTANCE);
+                nativetouch::hook(avs::game::DLL_INSTANCE);
 
 #if !SPICE_XP