[erp5_core] Use SameSite=None cookie
The Chrome dev team plans to change the default cookie behaviour by setting the
SameSite attribute to
This will break OfficeJS access for Chrome 80 users, as the cookie will not be send anymore when erp5 would be accessed from the external web site.
In order to keep the current functionalities, one quick solution is too manually set the
SameSite value to