iidx: detect ldj/tdj I/O mismatch (#470)

## Link to GitHub Issue, if one exists
#345 

## Description of change
For IIDX31+, detect if BI2A or BI2X I/O emulation becomes active, and
see if there is a mismatch between the -iidxtdj setting.

Right now a mismatch results in warning in log + deferred error log, but
in the future we could turn this into a fatal error and crash the game
to make it more obvious.

## Testing
Tested 4 combinations:

1. DLL in LDJ mode + -iidxtdj off (pass)
2. DLL in LDJ mode + -iidxtdj on (error)
3. DLL in TDJ mode + -iidxtdj off (error)
4. DLL in TDJ mode + -iidxtdj on (pass)

src/spice2x/games/iidx/iidx.h

@@ -62,4 +62,10 @@ namespace games::iidx {
     const char* get_16seg();
     bool is_tdj_fhd();
     void apply_audio_hacks();
+
+    enum class iidx_aio_emulation_state {
+        bi2a_com2,
+        bi2x_hook
+    };
+    void update_io_emulation_state(iidx_aio_emulation_state state);
 }