gitadora: various fixes for wailing (#513)

## Link to GitHub Issue, if one exists
Fixes #512

## Description of change
Fix digital wailing not being recognized consistently.

Also address the fact that wailing was completely broken when lefty mode
was on. This requires a new option that the user needs to check off in
the configurator since we can't magically guess if the user is holding
the guitar in lefty mode.

- [x] fix downward wail
- [x] digital lefty mode
- [x] implement all of this for arena model i/o
- [x] test dx cab 2p
- [x] lefty toggle in overlay
- [x] fix analog not working for 2p guitar
- [ ] analog lefty mode?

## Testing
Checked GW and GW Delta

src/spice2x/games/gitadora/gitadora.h

@@ -10,6 +10,8 @@ namespace games::gitadora {
     // settings
     extern bool TWOCHANNEL;
     extern std::optional<unsigned int> CAB_TYPE;
+    extern bool P1_LEFTY;
+    extern bool P2_LEFTY;
 
     class GitaDoraGame : public games::Game {
     public:
@@ -38,4 +40,12 @@ namespace games::gitadora {
             );
     }
 
+    static inline bool is_player_lefty(size_t player) {
+        if (player == 0) {
+            return P1_LEFTY;
+        } else if (player == 1) {
+            return P2_LEFTY;
+        }
+        return false;
+    }
 }