Implement process for testing "upgrade *from* current version"

We've hit a number of very serious problems over the past year or two because we lack a way to test the upgrade process from the version being developed. With RPM, Deb, and MSI packages there are various different nuances about what actions are performed during upgrade, so we need to check those pathways. But all of those packaging mechanisms prevent "upgrading" to the same version number, so we need to create some fake builds with higher version number to allow such testing.

QE will also need to consume those artifacts and perform upgrade tests on them.