Adding absorption and xp API, and weather control (#540)

* fixes #537
* fixes  #547

src/main/java/carpet/fakes/ServerWorldInterface.java

@@ -0,0 +1,7 @@
+package carpet.fakes;
+
+import net.minecraft.world.level.ServerWorldProperties;
+
+public interface ServerWorldInterface {
+    ServerWorldProperties getWorldPropertiesCM();
+}