popn: new cab lights (#629)

## Link to GitHub Issue or related Pull Request, if one exists
#618 

## Description of change
Basic support for lights - subwoofer RGB and button lights.

## Testing
Tested on title screen and in-game.

Tested beat pop as well since that lights up the colors in white/blue.

src/spice2x/games/popn/io.h

@@ -28,7 +28,7 @@ namespace games::popn {
 
     // all lights in correct order
     namespace Lights {
-        enum {
+        typedef enum {
             Button1,
             Button2,
             Button3,
@@ -85,7 +85,7 @@ namespace games::popn {
             WooferLED_R,
             WooferLED_G,
             WooferLED_B,
-        };
+        } popn_lights_t;
     }
 
     // getters