Implement Brigadier Mojang API

This is the start of a new module for Paper to add support for API's
that interface Mojang API's directly.

This allows us to version properly by MC version incase Mojang makes any major breaking changes.

It also lets us separate Mojang API's from Paper-API so our downstream friends at Glowstone
will not have to worry about Mojang code.

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

Spigot-Server-Patches/Handle-plugin-prefixes-using-Log4J-configuration.patch

@@ -15,7 +15,7 @@ This may cause additional prefixes to be disabled for plugins bypassing
 the plugin logger.
 
 diff --git a/pom.xml b/pom.xml
-index 14c4ec25..5a230592 100644
+index 24cdeb6ff4..ab8c61ab53 100644
 --- a/pom.xml
 +++ b/pom.xml
 @@ -0,0 +0,0 @@
@@ -28,7 +28,7 @@ index 14c4ec25..5a230592 100644
          <dependency>
              <groupId>org.apache.logging.log4j</groupId>
 diff --git a/src/main/java/org/spigotmc/SpigotConfig.java b/src/main/java/org/spigotmc/SpigotConfig.java
-index fdca3434..6d77bbc5 100644
+index fdca34346a..6d77bbc5aa 100644
 --- a/src/main/java/org/spigotmc/SpigotConfig.java
 +++ b/src/main/java/org/spigotmc/SpigotConfig.java
 @@ -0,0 +0,0 @@ public class SpigotConfig
@@ -41,7 +41,7 @@ index fdca3434..6d77bbc5 100644
  
      public static int playerShuffle;
 diff --git a/src/main/resources/log4j2.xml b/src/main/resources/log4j2.xml
-index 620b9490..a8bdaaea 100644
+index 620b9490e5..a8bdaaeaa1 100644
 --- a/src/main/resources/log4j2.xml
 +++ b/src/main/resources/log4j2.xml
 @@ -0,0 +0,0 @@