Change default name on nav button from next/back to Neste/Forrige

[Annikenkbrathen]

We should have Norwegian names on the buttons by default since the app is Norwegian by default. This is to spare the users the job of translating each navigation button. We should use the words 'forrige' and 'neste' as the design system recommends.

[nkylstad]

This can be solved in several ways:

• Add the text keys next and back with the Norwegian texts to the nb text resource file on app creation
• Add the text keys next and back with the Norwegian texts to the nb text resource file on add new page

The second option could use syncEvent architecture on backend, when adding a new page. See f.ex. process for example. When adding a new page, ensure that the next and back text keys are present in the norwegian nb text resource file, with the norwegian texts. Only add the keys next and back if they are not already added.