Fetch users e-mail address from Altinn profile into receipt page

## Description
As a user I want the option to be able to receive a copy of the PDF receipt on email.
As a user I want my e-mail to pre-filled after I submit a form. This e-mail address is for sending a receipt of a completed form.

## Screenshots
The screenshots shows the actual contact information values available on the profile, and is not intended for implementation in an app. The values are fetched from Kontakt- and reservasjonsregisteret (KRR).


## Considerations
There is a flag on the profile saying 'Jeg ønsker kvittering på e-post for innsendte skjema'. Although this states that the user always should get a receipt on e-mail if checked we probably need a way to opt-out of this for the application developers as we have scenarios where a receipt is not relevant.

## Acceptance criteria
- [ ] The e-mail address should be pre-filled with the users registered e-mail
- [ ] If the user has checked the 'Jeg ønsker kvittering på e-post for innsendte skjema' on the profile that should be respected by default

## Related issues
- Blocked by: https://github.com/Altinn/altinn-notifications/issues/148

## Tasks
- [ ] Look into how this should work if the user is representing an organization.

Start by reviewing the acceptance criteria and the linked Altinn Notifications issue 148, which blocks this work. Investigate how the receipt page receives profile data and how organization representation should behave. Done means the registered email is pre-filled and the profile’s email-receipt preference is respected by default, with an application opt-out considered.

Written by the indexing model from the issue text.