Implement "return to summary" button when navigating to field from Summary2

### Description

In the legacy `Summary` component, when you click to navigate to the source component, the 'next' button in `NavigationButtons` change the text to `Back to summary`, and will take you all the way to the page the `Summary` component was on.

This functionality should also be implemented for `Summary2` ([see NavigationButtonsComponent](https://github.com/Altinn/app-frontend-react/blob/4b5591a747e32cd6f957f78d2546321d135f9c8f/src/layout/NavigationButtons/NavigationButtonsComponent.tsx#L26)).

Alternatively, we should think through the user experience with this approach and make something even better to replace it all.

### Additional Information

- #2869
- #1862

Start with Summary2 and src/layout/NavigationButtons/NavigationButtonsComponent.tsx, then compare the legacy Summary navigation behavior described in the issue. Trace how navigation reaches the source component and define whether the requested button behavior or a revised user experience is intended. Done means the chosen behavior returns users to the Summary2 page and is verified in the relevant frontend flow.

Written by the indexing model from the issue text.