Add header for game list (#3)

Co-authored-by: Maxime Adler <madler@sqli.com>
Reviewed-on: #3

src/GameIdeas/Client/GameIdeas.BlazorApp/Services/AuthentificationService.cs

@@ -0,0 +1,21 @@
+namespace GameIdeas.BlazorApp.Services;
+
+public class AuthentificationService
+{
+    private bool isLogin;
+
+    public bool IsLogin
+    {
+        get { return isLogin; }
+    }
+
+    public void Login()
+    {
+        isLogin = true;
+    }
+
+    public void Logout()
+    {
+        isLogin = false;
+    }
+}