Add Mahjong Fight Girl Support (#275)

## Link to GitHub Issue, if one exists
n/a

## Description of change
Adds Mahjong Fight Girl Support

## Compiling
+

## Testing
Tested with VFG:J:E:A:2024100800 in HG mode with VFG IO. No
modifications made to data, other than avs-config.xml and
ea3-config.xml. B and C modes don't work because of serial touchscreen.
UKS mode doesn't work because of IO.

src/spice2x/games/mfg/io.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <vector>
+#include "cfg/api.h"
+
+namespace games::mfg {
+    namespace Buttons {
+        enum {
+            Service,
+            Test,
+            CoinMech,
+            ActionButton
+        };
+    }
+
+    // getters
+    std::vector<Button> &get_buttons();
+    std::string get_buttons_help();
+}