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/Fix-World-isChunkGenerated-calls.patch

@@ -8,7 +8,7 @@ This patch also adds a chunk status cache on region files (note that
 its only purpose is to cache the status on DISK)
 
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 6713b7667a..4c9c8e4839 100644
+index 6713b7667ae..4c9c8e48397 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 {
@@ -43,7 +43,7 @@ index 6713b7667a..4c9c8e4839 100644
  
      @Nullable
 diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
-index f54572773c..8e4b3e52cb 100644
+index f54572773c2..8e4b3e52cbc 100644
 --- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 +++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 @@ -0,0 +0,0 @@ public class ChunkRegionLoader {
@@ -65,7 +65,7 @@ index f54572773c..8e4b3e52cb 100644
          if (nbttagcompound != null) {
              ChunkStatus chunkstatus = ChunkStatus.a(nbttagcompound.getCompound("Level").getString("Status"));
 diff --git a/src/main/java/net/minecraft/server/ChunkStatus.java b/src/main/java/net/minecraft/server/ChunkStatus.java
-index efdf611e66..134a4f0b7d 100644
+index efdf611e66f..134a4f0b7d2 100644
 --- a/src/main/java/net/minecraft/server/ChunkStatus.java
 +++ b/src/main/java/net/minecraft/server/ChunkStatus.java
 @@ -0,0 +0,0 @@ public class ChunkStatus {
@@ -95,7 +95,7 @@ index efdf611e66..134a4f0b7d 100644
          return (ChunkStatus) IRegistry.CHUNK_STATUS.get(MinecraftKey.a(s));
      }
 diff --git a/src/main/java/net/minecraft/server/IChunkLoader.java b/src/main/java/net/minecraft/server/IChunkLoader.java
-index f0a052eec2..2f95174fcc 100644
+index f0a052eec2f..2f95174fcc4 100644
 --- a/src/main/java/net/minecraft/server/IChunkLoader.java
 +++ b/src/main/java/net/minecraft/server/IChunkLoader.java
 @@ -0,0 +0,0 @@ import javax.annotation.Nullable;
@@ -108,7 +108,7 @@ index f0a052eec2..2f95174fcc 100644
      @Nullable
      private PersistentStructureLegacy c;
 diff --git a/src/main/java/net/minecraft/server/PlayerChunk.java b/src/main/java/net/minecraft/server/PlayerChunk.java
-index 3d255b1964..040d4b41ea 100644
+index 3d255b19647..040d4b41ea2 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 {
@@ -132,7 +132,7 @@ index 3d255b1964..040d4b41ea 100644
  
      public CompletableFuture<Either<IChunkAccess, PlayerChunk.Failure>> getStatusFutureUnchecked(ChunkStatus chunkstatus) {
 diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
-index 4f5b516144..1d517fd1ae 100644
+index 4f5b5161448..1d517fd1aea 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 {
@@ -201,7 +201,7 @@ index 4f5b516144..1d517fd1ae 100644
          // Spigot start
          return isOutsideOfRange(chunkcoordintpair, false);
 diff --git a/src/main/java/net/minecraft/server/RegionFile.java b/src/main/java/net/minecraft/server/RegionFile.java
-index 6b543f89d4..d37abf2cf3 100644
+index 6b543f89d4e..d37abf2cf30 100644
 --- a/src/main/java/net/minecraft/server/RegionFile.java
 +++ b/src/main/java/net/minecraft/server/RegionFile.java
 @@ -0,0 +0,0 @@ public class RegionFile implements AutoCloseable {
@@ -250,7 +250,7 @@ index 6b543f89d4..d37abf2cf3 100644
              this.c();
          } finally {
 diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
-index 942b7d3239..2f8af42e2a 100644
+index 942b7d32393..2f8af42e2aa 100644
 --- a/src/main/java/net/minecraft/server/RegionFileCache.java
 +++ b/src/main/java/net/minecraft/server/RegionFileCache.java
 @@ -0,0 +0,0 @@ public final class RegionFileCache implements AutoCloseable {
@@ -280,7 +280,7 @@ index 942b7d3239..2f8af42e2a 100644
              throwable = throwable1;
              throw throwable1;
 diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
-index 8f8c18c5a4..50467656df 100644
+index 8f8c18c5a4f..50467656df0 100644
 --- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 +++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 @@ -0,0 +0,0 @@ import java.util.Objects;