[ADD] web: add widget button of Active/Deactive user.

[IMP] Improve user form view

- Task: https://www.odoo.com/web#id=7767&view_type=form&model=project.task&action=333&active_id=131
- Pad: https://pad.odoo.com/p/r.lFw6dVRQWxXWZUJk
Please avoid custom css for things like that. You may for example use jquery toggle() method, or add / remove items from the div, ... depending on your widget.