[ADD] Authentication via HTTP Remote User 8.0

Resubmit https://github.com/OCA/server-tools/pull/34 since the original PR was made on the master branch before the creation of the 8.0

The module allows integration with external security systems (Shibolleth, Tivoli access manager, ..) that can pass along authentication of a user via Remote_User HTTP header field. In many cases, this is achieved via server like Apache HTTPD or nginx proxying Odoo.