this pr has the basic plumbing that allows the e2e machine tests to run
with the hyperv provider.
it requires a special fcos image right now because gvforwarder was not
in the upstream fcos images for hyperv.
changed the way "provider" is set; moved GetProvider functions to
pkg/machine/provider. provider is now set at the machine level.
Signed-off-by: Brent Baude <bbaude@redhat.com>