Switch to using ForgeFlower for Paper Only mc-dev imports

ForgeFlower is better than Spigots FernFlower at decompiling the source.

However, in order to maintain the CraftBukkit patches, we must keep
using spigots for the primary.

However, for any file that we import on top of Spigots imported files
there is nothing stopping us from using better decompiled files.

So these changes will use ForgeFlower to maintain a better set of
decomped files, so anything we add on top of Paper can start off
in a better spot.

Spigot-Server-Patches/Entity-Origin-API.patch

@@ -89,7 +89,7 @@ index 5ceb3f2068..87f3205f82 100644
  
      @Nullable
 diff --git a/src/main/java/net/minecraft/server/NBTTagList.java b/src/main/java/net/minecraft/server/NBTTagList.java
-index a8280acf94..38dd8f17a6 100644
+index 769d599c59..e37da10e09 100644
 --- a/src/main/java/net/minecraft/server/NBTTagList.java
 +++ b/src/main/java/net/minecraft/server/NBTTagList.java
 @@ -0,0 +0,0 @@ public class NBTTagList extends NBTList<NBTBase> {
@@ -99,9 +99,9 @@ index a8280acf94..38dd8f17a6 100644
 +    public final double getDoubleAt(int i) { return this.k(i); } // Paper - OBFHELPER
      public double k(int i) {
          if (i >= 0 && i < this.list.size()) {
-             NBTBase nbtbase = (NBTBase) this.list.get(i);
+             NBTBase nbtbase = (NBTBase)this.list.get(i);
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index dc49d9917e..be2feb441d 100644
+index ce97cc99fa..cf359d6d9e 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
 @@ -0,0 +0,0 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc