[Libguestfs] [PATCH 0/3] v2v: -o rhv-upload: Add a test.

This adds a test of -o rhv-upload. Obviously for an upstream test we cannot require a working oVirt server. This test works by faking the ovirtsdk4 Python module, setting PYTHONPATH so that the fake module is picked up instead of the real module (if installed). However it's more complex than that because the nbdkit plugin also expects to talk to a working imageio HTTPS server. Therefore the fake ovirtsdk4 module also starts a web server running on a random port which looks sufficiently similar to a real imageio server to trick virt-v2v (but any data written is discarded). This test is designed to pick up only gross errors, such as the one where we recently shipped a non-working -o rhv-upload mode in RHEL 7.6 LP. Rich.