Implement EnderCrystal#isShowingBottom and EnderCrystal#setShowingBottom(boolean)

By: Matthew <stteg@hotmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftEnderCrystal.java

@@ -10,6 +10,16 @@ public class CraftEnderCrystal extends CraftEntity implements EnderCrystal {
         super(server, entity);
     }
 
+    @Override
+    public boolean isShowingBottom() {
+        return getHandle().k(); // PAIL: Rename isShowingBottom
+    }
+
+    @Override
+    public void setShowingBottom(boolean showing) {
+        getHandle().a(showing); // PAIL: Rename setShowingBottom
+    }
+
     @Override
     public EntityEnderCrystal getHandle() {
         return (EntityEnderCrystal) entity;