fix(checkout): add missing JSInterop import for enhanced interactivity

- Included the Microsoft.JSInterop namespace in the Checkout.razor.cs file to enable JavaScript interop functionality.
- This addition prepares the Checkout component for future enhancements that may require interaction with JavaScript libraries or functions.

These changes improve the potential for interactive features in the checkout process, enhancing user experience.

src/FrontOffice.Main/Pages/Checkout.razor.cs

@@ -1,6 +1,7 @@
 using CMSMicroservice.Protobuf.Protos.Package;
 using FrontOffice.Main.Utilities;
 using Microsoft.AspNetCore.Components;
+using Microsoft.JSInterop;
 using MudBlazor;
 using Severity = MudBlazor.Severity;