Description of the bug

If you send some invalid data to the payment provider, it seems that the payment GUI gets stuck instead of showing that something failed, and allowing for retry or clicking "Tilbake".

Think about: Any value gained if we let TE to inspect errors received from a payment processor and act on it in C# code? Think a bit about if we could return a result from payment processor that contains some error information. Maybe user actions could return text resource keys for known errors, that could be displayed in the GUI. Extendable with custom text resources.

Acceptance criteria:

• Display that something failed.
• Show the "Betal" button so that retries are possible.
• Show "Tilbake" button if reject is configured.

Steps To Reproduce

1. Use an app that has payment with Nets Easy configured. For instance: https://ttd.apps.tt02.altinn.no/ttd/payment-test-nets.
2. Enter an invalid zip code as part of "Søkeren"'s address. For instance 11111.
3. Enter some goods and services.
4. Proceed to payment step.
5. See in the developer console that the API call to pay-action fails, and that GUI gets stuck.

Additional Information

No response