Rework the inventory unit tests by splitting up
tests/unit/plugins/inventory/test_kubevirt.py into multiple files,
by trying to simplify the test code and making it more robust and by
using appropriate fixtures. This also adds new tests or test cases to
improve code coverage. Tests that work from the black box perspective
are now located in a subdirectory.
Signed-off-by: Felix Matouschek <fmatouschek@redhat.com>
