This commit provides a test suite for sale flow and unit tests.
We split tests in different files to try regrouping them by
testing purpose:
1/ test_access_rights.py checks employee, sale person, sale manager
and portal access rights. It is executes in post-install mode to be
sure other addons does not break the security rules.
2/ test_onchange.py checks the onchange using the SFF mecanism in
order to simulate what a sale person really does in its day-to-day
job.
3/ test_sale_pricelist.py execute a sale flow with different pricelist,
as this is a delicate aspect.
4/ test_sale_to_invoice.py contains tests about refund, discount and
downpayment, as none of those were tested.
Task #43928