[fix]crm: added code to display total number of opportunities including ...

...opportunities of its child if customer is company

Task: https://www.odoo.com/web#id=9573&view_type=form&model=project.task&menu_id=3942&action=327
PAD: https://pad.odoo.com/p/r.APoK0kZpXAPjW0KE
@hmo-odoo  , @rim-odoo  this diff is not from my branch!!