api: add sound volume accessors and vars

runelite-api/src/main/java/net/runelite/api/Client.java

@@ -944,6 +944,42 @@ public interface Client extends GameEngine
 	 */
 	List<GraphicsObject> getGraphicsObjects();
 
+	/**
+	 * Gets the music volume
+	 * @return volume 0-255 inclusive
+	 */
+	int getMusicVolume();
+
+	/**
+	 * Sets the music volume
+	 * @param volume 0-255 inclusive
+	 */
+	void setMusicVolume(int volume);
+
+	/**
+	 * Gets the sound effect volume
+	 * @return volume 0-127 inclusive
+	 */
+	int getSoundEffectVolume();
+
+	/**
+	 * Sets the sound effect volume
+	 * @param volume 0-127 inclusive
+	 */
+	void setSoundEffectVolume(int volume);
+
+	/**
+	 * Gets the area sound effect volume
+	 * @return volume 0-127 inclusive
+	 */
+	int getAreaSoundEffectVolume();
+
+	/**
+	 * Sets the area sound effect volume
+	 * @param volume 0-127 inclusive
+	 */
+	void setAreaSoundEffectVolume(int volume);
+
 	/**
 	 * Play a sound effect at the player's current location. This is how UI,
 	 * and player-generated (e.g. mining, woodcutting) sound effects are

runelite-api/src/main/java/net/runelite/api/VarPlayer.java

@@ -162,7 +162,11 @@ public enum VarPlayer
 	MUSIC_TRACKS_UNLOCKED_16(1009),
 	MUSIC_TRACKS_UNLOCKED_17(1338),
 	MUSIC_TRACKS_UNLOCKED_18(1681),
-	MUSIC_TRACKS_UNLOCKED_19(2065);
+	MUSIC_TRACKS_UNLOCKED_19(2065),
+
+	MUSIC_VOLUME(168),
+	SOUND_EFFECT_VOLUME(169),
+	AREA_EFFECT_VOLUME(872);
 
 	private final int id;
 }