To prevent the invite id from showing up in various logs along the way,
we change to use an anchor in the invite url, and a post request to the
backend.

Invite links are now on the form /invitelink/#<uuid> and the frontend
redirects to /invite as usual after the session has been created.

Resolves: GREG-90

Even though start_date can be optional in the payload, it will always be
present in the form.

Code for guest routes moved to their own folder so that we don't need
multiple api calls.
Serializer class for roles has been simplified with methods for
validation of each field and a separate one used in invites without
requiring the person field.

Resolves: GREG-61

Breaks npm build

Issue: GREG-96

Issue: GREG-96

Allows search using e-mail and mobile phone, limiting results to 10
first matches

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.

When choosing the Register new guest button, you are now sent to a new
page where you can search for existing guests to prevent creating
duplicates. The page also has a register new guest button that takes you
to the previous version of the page, now located at /register/new

A future commit will make the search field functional.

Code for registering a new guest has been moved to
register/stepRegistration.tsx to make room for multiple routes in
register/index.tsx.

Will be shown in header, so not needed on page as well

Issue: GREG-75

Issue: GREG-75

Issue: GREG-75