fix(core): Adds SkipLocalsInitAttribute support, optimizes broadcasted packets (#363)

- [X] Adds support for `SkipLocalsInitAttribute`. SkipLocalsInitAttribute skips initializing stack variables including `stackalloc`. I don't think it is wired/working yet but should be implemented soon.
- [X] Optimizes broadcasted packets by checking if the first byte (packet ID) is non-zero. If it is already set, it reuses the buffer.
- [X] Removes unnecessary refs to Spans. I don't think the Span struct itself is mutable, so a ref is not helpful.

Projects/Server/World/World.cs

@@ -154,8 +154,7 @@ namespace Server
 
             Span<byte> buffer = stackalloc byte[length];
             length = OutgoingMessagePackets.CreateMessage(
-                ref buffer,
-                Serial.MinusOne, -1, MessageType.Regular, hue, 3, ascii, "ENU", "System", text
+                buffer, Serial.MinusOne, -1, MessageType.Regular, hue, 3, ascii, "ENU", "System", text
             );
 
             buffer = buffer.Slice(0, length); // Adjust to the actual size