Add initial server implementation

This adventure is going to be epic, be ready.

board-network/src/protocol.rs

@@ -0,0 +1,15 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub enum ClientMessage {
+    CreateRoom(String),
+    JoinRoom(String, String),
+    Disconnected,
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub enum ServerMessage {
+    JoinedRoom {
+        room_name: String,
+    },
+}