Add WORLD_IMMUTABLE flag to spectator mode (#1034)

Prevents the client from trying to interact with blocks

connector/src/main/java/org/geysermc/connector/network/translators/java/world/JavaNotifyClientTranslator.java

@@ -85,6 +85,7 @@ public class JavaNotifyClientTranslator extends PacketTranslator<ServerNotifyCli
                     playerFlags.add(AdventureSetting.MAY_FLY);
                     playerFlags.add(AdventureSetting.NO_CLIP);
                     playerFlags.add(AdventureSetting.FLYING);
+                    playerFlags.add(AdventureSetting.WORLD_IMMUTABLE);
                     gameMode = GameMode.CREATIVE; // spectator doesnt exist on bedrock
                 }