Add trait to obtain protocol packet ID from packet data

protocol/src/version/mod.rs

@@ -1,2 +1,19 @@
 pub mod v1_14_4;
 pub mod v1_17_1;
+
+/// Trait to obtain packet ID from packet data.
+pub trait PacketId {
+    /// Get protcol packet ID.
+    fn packet_id(&self) -> u8;
+}
+
+#[macro_export]
+macro_rules! trait_packet_id (
+    ($type: ident, $id: expr) => (
+        impl PacketId for $type {
+            fn packet_id(&self) -> u8 {
+                $id
+            }
+        }
+    )
+);