Added user management endpoints

src/HopFrame.Api/Models/UserCreator.cs

@@ -0,0 +1,8 @@
+namespace HopFrame.Api.Models;
+
+public class UserCreator {
+    public string Username { get; set; }
+    public string Email { get; set; }
+    public string Password { get; set; }
+    public virtual List<string> Permissions { get; set; }
+}