To make handling info about roles and persons easier we split them into
separate objects. The Profile page has now gotten its own api endpoint
where a sponsor has access to all guests instead of only those they are
sponsor for which is used on the sponsor frontpage. This is necessary
since a sponsor may want to give a role to someone they are not
currently sponsor for.

Allows changes to start- and end date for guest roles. A new endpoint
has been added to the ui api for doing PATCH request to support this.
The max days of each role type is respected.

Resolves: GREG-83

- Expanded output from guest info api endpoint
- Share guest info between both routes under /sponsor of the frontend.
- More localised text options added for use on the sponsor pages
- Details button on the sponsor overview page now points to the guest
  info page for each person.

Resolves: GREG-74

Issue: GREG-66

- Introduces the Invitation and InvitationLink models for keeping track
  of guest invitations and the links connected to them.
- Adds a post endpoint accessible by sponsors to create invitations for
  guests.
- Adds a get endpoint for the guests to review their invitation
  information.
- Adds a post endpoint for the guests to confirm their invitation with
  updated mobile_phone number if they want.
- Removes token field from Person since it is not used.

Register page now fetches OUs the sponsor has access to.
Sponsor page now shows the sponsor's active and waiting guests.

Resolves: GREG-63

Issue: GREG-36

Issue: GREG-35