Purpose
=========

Ease sharing of appointment, notably when they are not published. This allows to be more
flexible with appointment types we need to share.

Cleanup model names now that most appointment features landed into master.

Specifications
================

When an appointment type is unpublished, it can now be shared thanks to a
token. It is linked to an invite which is a new model storing parameters
of a specific invite, along with the token and parameters (appointment types,
filtered users to display, ...). This globally replaces the old share wizard
and is now a real model to ease token (re)usage.

It is intended to work whatever the status of published field, which is now
moved directly into appointment module. Publishing just eases visibility
and allow to access an appointment type without invite.

Now public user cannot read all appointment types without the website module.

We also display the unpublished appointment types in the "Share Availabilities"
dropdown, which creates now an invitation.

Renaming
==========

Rename appointment models and main routes to get rid of "calendar" prefix as
appointment is now a complete app, even if build on top of calendar. Old routes
are kept for backward compatibility, notably for people that saved a link to use for
their customers.

Links
======

Task-2716094