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/Reduce-sync-loads.patch

@@ -11,7 +11,7 @@ it must be enabled by setting the startup flag -Dpaper.debug-sync-loads=true
 To get a debug log for sync loads, the command is /paper syncloadinfo
 
 diff --git a/src/main/java/com/destroystokyo/paper/PaperCommand.java b/src/main/java/com/destroystokyo/paper/PaperCommand.java
-index af81098784..ddb60e9a48 100644
+index af810987846..ddb60e9a48e 100644
 --- a/src/main/java/com/destroystokyo/paper/PaperCommand.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperCommand.java
 @@ -0,0 +0,0 @@
@@ -108,7 +108,7 @@ index af81098784..ddb60e9a48 100644
          if (args.length < 2 || args[1].equals("*")) {
 diff --git a/src/main/java/com/destroystokyo/paper/io/SyncLoadFinder.java b/src/main/java/com/destroystokyo/paper/io/SyncLoadFinder.java
 new file mode 100644
-index 0000000000..59aec10329
+index 00000000000..59aec103295
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/SyncLoadFinder.java
 @@ -0,0 +0,0 @@
@@ -285,7 +285,7 @@ index 0000000000..59aec10329
 +    }
 +}
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 259af7095c..ea1117dc86 100644
+index 259af7095c4..ea1117dc86e 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
@@ -297,7 +297,7 @@ index 259af7095c..ea1117dc86 100644
              this.serverThreadQueue.awaitTasks(completablefuture::isDone);
                  com.destroystokyo.paper.io.chunk.ChunkTaskManager.popChunkWait(); // Paper - async chunk debug
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 311685180f..568e04faa3 100644
+index 311685180fe..568e04faa31 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 GeneratorAccess, AutoCloseable {
@@ -328,7 +328,7 @@ index 311685180f..568e04faa3 100644
                  if (chunk != null) {
                      chunk.a(oclass, axisalignedbb, list, predicate);
 diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
-index 3db0ad0a46..5f2c425129 100644
+index c0476f69e4a..2fa1b86adf8 100644
 --- a/src/main/java/net/minecraft/server/WorldServer.java
 +++ b/src/main/java/net/minecraft/server/WorldServer.java
 @@ -0,0 +0,0 @@ public class WorldServer extends World {