User language is not set correct in cookies

[mgunnerud]

Description of the bug

We are currently unable to read the language from users cookie, so the fallback language norwegian bokmål will always be used.

Two issues should be fixed to get correct language cookie:

• The cookie should be named i18next, not il8next as it is currently named in code. (the lower-case L must be replaced with the number 1)
• The returned language code is not what the frontend expects. Frontend expects either no_nb, no_nn or en. Currently the cookie value is set to simply nb. https://github.com/Altinn/altinn-access-management-frontend/blob/main/backend/src/Altinn.AccessManagement.UI/Altinn.AccessManagement.UI.Core/Helpers/ProfileHelper.cs appears to do it correctly

Steps To Reproduce

1. Go to frontend solution
2. Check cookies, see that cookie name is not the expected cookie name

Additional Information

No response