WCAG: That a link take you out of the app (external) are only communicated trough an icon

### Description of the bug

When using links that go out of the app it is common to have an arrow icon on the end of the link to indicate that you are leaving the page you are currently on if you use the link. But this information should also be communicated to screen readers.

This is handled on Altinn.no today and should be handled in similar way for Altinn 3 apps.

[Example from Altinn.no:](https://www.altinn.no/om-altinn/hva-er-altinn/)

### Steps To Reproduce

Use a screen reader on an external link in an application
There should be no indication that you are leaving the area you are in.

### Additional Information

_No response_

Start by locating the frontend component or entry point that renders external links, then compare its accessible output with the Altinn.no example linked in the issue. Done means a screen reader receives an indication that the link leaves the current app or page, in addition to the visual arrow icon.

Written by the indexing model from the issue text.