[Add]crm: Added feature of 'Schedule/Log call' for opportunity form view...

... and counting no. of calls
https://www.odoo.com/web?#id=9692&view_type=form&model=project.task&menu_id=3942&action=327
pad link: https://pad.odoo.com/p/r.50gngfEsc7owm22s
use meaningful name of `record`