[FIX] hr: do not show employee users to portal users
[FIX] hr: do not show employee users to portal users

When you are connected as a portal user, you can connect to the
backend of Odoo and if you go to your discuss app through the '@' icon,
you can list the employees of the company by mention a employee

This is caused by a SQL request that store in cache the employee
list to minimize requests when mention. The problem
is that those requests don't take into account the rights of a user
to read employees information.

To fix this, we are taking the group 'base.group_user' and read the
information of its users, the 'read' is respecting, the access rights of
the users, and so the employees names, are ont shown anymore to portal
users.

opw-704127

hip-odoo/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,ygol/odoo,bplancher/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo,ygol/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,bplancher/odoo,ygol/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,laslabs/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,dfang/odoo,bplancher/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,dfang/odoo,hip-odoo/odoo,dfang/odoo,bplancher/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,dfang/odoo