refactor: split server into mutliples methods

app/src/main/java/clientserver/App.java

@@ -1,7 +1,7 @@
 package clientserver;
 
 import clientserver.client.Client;
-import clientserver.server.ClientHandler;
+import clientserver.server.Server;
 
 public class App {
 
@@ -28,7 +28,7 @@ public class App {
             case "server":
                 // Run the server
                 System.out.println("Starting server...");
-                ClientHandler.main(new String[] {});
+                Server.run();
                 break;
             default:
                 System.out.println("Unknown mode: " + mode);