Resolve "Login screen setup (without backend)"

Closes #19 (closed)

frontend/core/src/com/game/tankwars/controller/LoginController.java

+package com.game.tankwars.controller;
+
+import com.badlogic.gdx.math.Vector3;
+import com.game.tankwars.TankWarsGame;
+
+public class LoginController {
+
+    private final TankWarsGame tankWarsGame;
+
+    public LoginController(final TankWarsGame tankWarsGame) {
+        this.tankWarsGame = tankWarsGame;
+    }
+
+    public void handleInput(Vector3 touchPos) {
+        System.out.println(touchPos);
+    }
+
+}