test: wire up networkValidateTests()

test: wire up networkValidateTests()

Our network driver calls networkValidate() right after a network
XML is parsed. This is similar to domain validation step when
parsing domain XML. But it's not that convoluted in network
driver. Regardless, any network related test should mimic real
life scenario as close as possible and thus
networkValidateTests() should be called right after domain XML is
parsed.

Now, networkValidate() might query sysfs wrt to PCI devices and
thus tests must start using virpcimock. The function will also
generate random MAC addresses, if needed, hence virrandommock.

With this change, passthrough-pf and passthrough-address-crash
test cases of networkxml2xmltest started failing but looking at
corresponding XMLs those test cases were designed to test just
XML parsing. They were never designed to showcase a "real"
network XML. So mark them as expected fail.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>