[FW][IMP] General: Google Oauth Docs edit

[fw-bot]

Targets 14.0 onward.

Google Oauth Changes to Sign-On, Calendar, Gmail
Changes: update to match new interface and remove second person, add details on Internal and External User Types.

Google Calendar Sync doc
https://www.odoo.com/web#id=3246409&cids=3&menu_id=4720&action=333&active_id=3835&model=project.task&view_type=form

[Calendar] Google Sync warning
https://www.odoo.com/web#id=3000531&cids=3&menu_id=4720&action=333&active_id=3835&model=project.task&view_type=form

Google Calendar Sync Videos
https://www.odoo.com/web#id=2859258&cids=3&menu_id=4720&action=333&active_id=3835&model=project.task&view_type=form

Google Sign-In Authentication User Type
https://www.odoo.com/web#id=3247706&cids=3&menu_id=4720&action=333&active_id=3835&model=project.task&view_type=form

[auth] rewrite google.rst
https://www.odoo.com/web#id=3252200&cids=3&model=project.task&view_type=form

Forward-Port-Of: #3965

[robodoo]

Pull request status dashboard.

[fw-bot]

This PR targets 16.0 and is part of the forward-port chain. Further PRs will be created up to master.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port