QNAM jobs: Make sure there is an etag is proper and not changed when one resume

Those tests are existing on the legacy jobs.

We check there is an etag so we make sure a proxy is not in between.
(We have seen user complaining because their proxy is replacing the
pages with one that says they need to enter their login and password)

Also it is important to check that the etag has not changed if we resume
(this may happen if the file is changed on the server between the update
phase and the propagate phase,  and that we resume this file)