Purpose
=======
As it has been done for Gmail, we want to add the OAuth authentication
for the incoming / outgoing mail server.

Specifications
==============
The user has to create a project on Outlook and fill the credentials
in Odoo. Once it's done, he can create an incoming / outgoing mail
server.

For the authentication flow is a bit different from Gmail. For Outlook
the user is redirected to Outlook where he'll accept the permission.
Once it's done, he's redirected again to the mail server form view and
the tokens are automatically added on the mail server.

Technical
=========
There are 3 tokens used for the OAuth authentication.
1. The authentication code. This one is only used to get the refresh
   token and the first access token. It's the code returned by the user
   browser during the authentication flow.
2. The refresh token. This one will never change once the user is
   authenticated. This token is used to get new access token once they
   are expired.
3. The access token. Those tokens have an expiration date (1 hour) and
   are used in the XOAUTH2 protocol to authenticate the IMAP / SMTP
   connection.

During the authentication process, we can also give a state that will
be returned by the user browser. This state contains
1. The model and the ID of the mail server (as the same mixin manage
   both incoming and outgoing mail server)
2. A CSRF token which sign those values and is verified once the browser
   redirect the user to the Odoo database. This is useful so a malicious
   user can not send a link to an admin to disconnect the mail server.

Task-2751996

X-original-commit: e54d63b3c0f39fd8a05e430442cf84d1d6c8de78
Part-of: odoo/odoo#87498