Name adjustments and moved some things to the common lib.

SharpChat/C2SPacketHandlerContext.cs

@@ -0,0 +1,19 @@
+namespace SharpChat {
+    public class C2SPacketHandlerContext(
+        string text,
+        Context chat,
+        Connection connection
+    ) {
+        public string Text { get; } = text ?? throw new ArgumentNullException(nameof(text));
+        public Context Chat { get; } = chat ?? throw new ArgumentNullException(nameof(chat));
+        public Connection Connection { get; } = connection ?? throw new ArgumentNullException(nameof(connection));
+
+        public bool CheckPacketId(string packetId) {
+            return Text == packetId || Text.StartsWith(packetId + '\t');
+        }
+
+        public string[] SplitText(int expect) {
+            return Text.Split('\t', expect + 1);
+        }
+    }
+}