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/Use-asynchronous-Log4j-2-loggers.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Use asynchronous Log4j 2 loggers
 
 
 diff --git a/pom.xml b/pom.xml
-index 6f2fe9c2..55679af9 100644
+index 76ce7f4486..28ff064c19 100644
 --- a/pom.xml
 +++ b/pom.xml
 @@ -0,0 +0,0 @@
@@ -24,7 +24,7 @@ index 6f2fe9c2..55679af9 100644
              <artifactId>asm</artifactId>
 diff --git a/src/main/java/com/destroystokyo/paper/log/LogFullPolicy.java b/src/main/java/com/destroystokyo/paper/log/LogFullPolicy.java
 new file mode 100644
-index 00000000..db652a1f
+index 0000000000..db652a1f7a
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/log/LogFullPolicy.java
 @@ -0,0 +0,0 @@
@@ -46,7 +46,7 @@ index 00000000..db652a1f
 +    }
 +}
 diff --git a/src/main/resources/log4j2.component.properties b/src/main/resources/log4j2.component.properties
-index 0694b214..30efeb5f 100644
+index 0694b21465..30efeb5faf 100644
 --- a/src/main/resources/log4j2.component.properties
 +++ b/src/main/resources/log4j2.component.properties
 @@ -1 +1,3 @@