Add some helpers to tidy up XAP (#20235)

quantum/audio/audio.h

@@ -63,6 +63,11 @@ typedef struct {
 
 // public interface
 
+/**
+ * @brief Save the current choices to the eeprom
+ */
+void eeconfig_update_audio_current(void);
+
 /**
  * @brief one-time initialization called by quantum/quantum.c
  * @details usually done lazy, when some tones are to be played