[Bleeding] Undo changes to the tree WorldGenerators.

- All StructureGrowEvent handling for these is in BlockSapling now, using a BlockChangeDelegate to collect the data.
- Moved StructureGrowDelegate into a separate class

By: Zeerix <zeerix@draig.de>

paper-server/src/main/java/org/bukkit/craftbukkit/util/StructureGrowDelegate.java

@@ -0,0 +1,48 @@
+package org.bukkit.craftbukkit.util;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import net.minecraft.server.World;
+
+import org.bukkit.BlockChangeDelegate;
+import org.bukkit.block.BlockState;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.material.MaterialData;
+
+public class StructureGrowDelegate implements BlockChangeDelegate {
+    private final CraftWorld world;
+    private final List<BlockState> blocks = new ArrayList<BlockState>();
+
+    public StructureGrowDelegate(World world) {
+        this.world = world.getWorld();
+    }
+
+    @Override
+    public boolean setRawTypeId(int x, int y, int z, int type) {
+        return setRawTypeIdAndData(x, y, z, type, 0);
+    }
+
+    @Override
+    public boolean setRawTypeIdAndData(int x, int y, int z, int type, int data) {
+        BlockState state = world.getBlockAt(x, y, z).getState();
+        state.setTypeId(type);
+        state.setData(new MaterialData(type, (byte) data));
+        blocks.add(state);
+        return true;
+    }
+
+    @Override
+    public int getTypeId(int x, int y, int z) {
+        return world.getBlockTypeIdAt(x, y, z);
+    }
+
+    @Override
+    public int getHeight() {
+        return world.getMaxHeight();
+    }
+
+    public List<BlockState> getBlocks() {
+        return blocks;
+    }
+}