Add register page, associated view model and successfully call service that just sends back received data

Models/ViewModels/ServiceResponse.cs

@@ -0,0 +1,8 @@
+namespace Sandbox.Models.ViewModels;
+
+public class ServiceResponse<T>
+{
+    public T? Data { get; set; }
+    public bool Success { get; set; } = true;
+    public string Message { get; set; } = string.Empty;
+}