Support custom server avatar

src/main/java/emu/grasscutter/Config.java

@@ -70,6 +70,7 @@ public final class Config {
 		public int MaxAvatarsInTeamMultiplayer = 4;
 		public int MaxEntityLimit = 1000; // Max entity limit per world. // TODO: Enforce later.
 		public boolean WatchGacha = false;
+		public int ServerAvatarId = 10000007;
 		public int[] WelcomeEmotes = {2007, 1002, 4010};
 		public String WelcomeMotd = "Welcome to Grasscutter emu";
 		public String WelcomeMailContent = "Hi there!\r\nFirst of all, welcome to Grasscutter. If you have any issues, please let us know so that Lawnmower can help you! \r\n\r\nCheck out our:\r\n<type=\"browser\" text=\"Discord\" href=\"https://discord.gg/T5vZU6UyeG\"/> <type=\"browser\" text=\"GitHub\" href=\"https://github.com/Melledy/Grasscutter\"/>";

src/main/java/emu/grasscutter/GameConstants.java

@@ -11,6 +11,7 @@ public final class GameConstants {
 	public static final int MAX_TEAMS = 4;
 	public static final int MAIN_CHARACTER_MALE = 10000005;
 	public static final int MAIN_CHARACTER_FEMALE = 10000007;
+	public static final int SERVER_AVATAR_ID = Grasscutter.getConfig().getGameServerOptions().ServerAvatarId;
 	public static final Position START_POSITION = new Position(2747, 194, -1719);
 	
 	public static final int MAX_FRIENDS = 45;

src/main/java/emu/grasscutter/server/packet/send/PacketGetPlayerFriendListRsp.java

@@ -20,7 +20,7 @@ public class PacketGetPlayerFriendListRsp extends BasePacket {
 				.setUid(GameConstants.SERVER_CONSOLE_UID)
 				.setNickname("Server")
 				.setLevel(1)
-				.setProfilePicture(ProfilePicture.newBuilder().setAvatarId(GameConstants.MAIN_CHARACTER_FEMALE))
+				.setProfilePicture(ProfilePicture.newBuilder().setAvatarId(GameConstants.SERVER_AVATAR_ID))
 				.setWorldLevel(0)
 				.setSignature("")
 				.setLastActiveTime((int) (System.currentTimeMillis() / 1000f))