gitadora: (arena model) asio option (#718)

## Link to GitHub Issue or related Pull Request, if one exists
#717 

## Description of change
Add an option to override the ASIO device.

By default the game will try to use any ASIO driver that contains the
string `XONAR` in it.

## Testing
Tested with FlexASIO.

src/spice2x/CMakeLists.txt

@@ -416,6 +416,7 @@ set(SOURCE_FILES ${SOURCE_FILES}
         games/nost/io.cpp
         games/nost/poke.cpp
         games/gitadora/gitadora.cpp
+        games/gitadora/asio.cpp
         games/gitadora/io.cpp
         games/gitadora/handle.cpp
         games/gitadora/j32d.cpp