[POS] Navigate to built-in screens using Navigation API

[camelmasa]

Please list the related package(s)

@shopify/ui-extensions-react/point-of-sale npm

If this related to specific APIs or components, please list them here

• useApi
• api.navigation.navigate()

Describe the changes you are looking for

I would like to be able to navigate to built-in screens (e.g., Cart or Customer screens) using api.navigation.navigate(). Currently, navigation is only possible to custom screens, but enabling direct access to built-in screens from the app would enhance the user experience.

[rgdagir]

+1!