Optimize Network Manager to not need synchronization

Removes synchronization from sending packets
Makes normal packet sends no longer need to be wrapped and queued like it use to work.
Adds more packet queue immunities on top of keep alive to let the following scenarios go out
without delay:
  - Keep Alive
  - Chat
  - Kick
  - All of the packets during the Player Joined World event

Hoping that latter one helps join timeout issues more too for slow connections.

Removes processing packet queue off of main thread
  - for the few cases where it is allowed, order is not necessary nor
    should it even be happening concurrently in first place (handshaking/login/status)

Ensures packets sent asynchronously are dispatched on main thread

This helps ensure safety for ProtocolLib as packet listeners
are commonly accessing world state. This will allow you to schedule
a packet to be sent async, but itll be dispatched sync for packet
listeners to process.

This should solve some deadlock risks

This may provide a decent performance improvement because thread synchronization incurs a cache reset
so by avoiding ever entering a synchronized block, we get to avoid that, and packet sending is a really
hot activity.

Spigot-Server-Patches/Chunk-debug-command.patch

@@ -32,7 +32,7 @@ https://bugs.mojang.com/browse/MC-141484?focusedCommentId=528273&page=com.atlass
 https://bugs.mojang.com/browse/MC-141484?focusedCommentId=528577&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-528577
 
 diff --git a/src/main/java/com/destroystokyo/paper/PaperCommand.java b/src/main/java/com/destroystokyo/paper/PaperCommand.java
-index 5acad8e44f..af81098784 100644
+index 5acad8e44f0..af810987846 100644
 --- a/src/main/java/com/destroystokyo/paper/PaperCommand.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperCommand.java
 @@ -0,0 +0,0 @@ public class PaperCommand extends Command {
@@ -185,7 +185,7 @@ index 5acad8e44f..af81098784 100644
       * Ported from MinecraftForge - author: LexManos <LexManos@gmail.com> - License: LGPLv2.1
       */
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 8c6550433c..e6d08756f7 100644
+index 8c6550433c2..e6d08756f76 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ import org.apache.logging.log4j.Logger;
@@ -198,7 +198,7 @@ index 8c6550433c..e6d08756f7 100644
      public final ChunkGenerator<?> chunkGenerator;
      private final WorldServer world;
 diff --git a/src/main/java/net/minecraft/server/MCUtil.java b/src/main/java/net/minecraft/server/MCUtil.java
-index 3342278bcd..2dcecc1bbd 100644
+index 3342278bcd4..2dcecc1bbd0 100644
 --- a/src/main/java/net/minecraft/server/MCUtil.java
 +++ b/src/main/java/net/minecraft/server/MCUtil.java
 @@ -0,0 +0,0 @@ import com.destroystokyo.paper.block.TargetBlockInfo;
@@ -399,7 +399,7 @@ index 3342278bcd..2dcecc1bbd 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/PlayerChunk.java b/src/main/java/net/minecraft/server/PlayerChunk.java
-index 6e9f402fb0..a640cb3845 100644
+index 6e9f402fb0f..a640cb3845a 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunk.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunk.java
 @@ -0,0 +0,0 @@ public class PlayerChunk {
@@ -412,7 +412,7 @@ index 6e9f402fb0..a640cb3845 100644
      private int dirtyCount;
      private int r;
 diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
-index 3c237b259e..6122d19ccf 100644
+index 1d255ce3833..34f470779fa 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
 @@ -0,0 +0,0 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
@@ -434,7 +434,7 @@ index 3c237b259e..6122d19ccf 100644
      private final DefinedStructureManager definedStructureManager;
      private final File w;
 diff --git a/src/main/java/net/minecraft/server/Ticket.java b/src/main/java/net/minecraft/server/Ticket.java
-index 77bb6b092a..7a8397815a 100644
+index 77bb6b092a0..7a8397815a5 100644
 --- a/src/main/java/net/minecraft/server/Ticket.java
 +++ b/src/main/java/net/minecraft/server/Ticket.java
 @@ -0,0 +0,0 @@ public final class Ticket<T> implements Comparable<Ticket<?>> {