Brigadier Mojang API

Adds AsyncPlayerSendCommandsEvent
  - Allows modifying on a per command basis what command data they see.

Adds CommandRegisteredEvent
  - Allows manipulating the CommandNode to add more children/metadata for the client

paper-server/patches/sources/com/mojang/brigadier/tree/CommandNode.java.patch

@@ -16,10 +16,11 @@
  
  public abstract class CommandNode<S> implements Comparable<CommandNode<S>> {
      private final Map<String, CommandNode<S>> children = new LinkedHashMap<>();
-@@ -32,6 +34,13 @@
+@@ -32,6 +34,14 @@
      private final RedirectModifier<S> modifier;
      private final boolean forks;
      private Command<S> command;
++    public CommandNode<CommandSourceStack> clientNode; // Paper - Brigadier API
 +    // CraftBukkit start
 +    public void removeCommand(String name) {
 +        this.children.remove(name);
@@ -30,7 +31,7 @@
  
      protected CommandNode(final Command<S> command, final Predicate<S> requirement, final CommandNode<S> redirect, final RedirectModifier<S> modifier, final boolean forks) {
          this.command = command;
-@@ -61,7 +70,17 @@
+@@ -61,7 +71,17 @@
          return this.modifier;
      }