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

- 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.

Make all URLs relative. Move /oidc and /admin endpoints up from /api and proxy them during development.

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

Resolves: GREG-63

- Add routing with react routing
- Placeholder header/footer and some pages

Issue: GREG-46