run: Add --run-dropin option

Add a run option that executes scripts on a directory
called dropin sequentially in the host, rather than
the guest. The option to run the mentioned tests in
the host will be added on a future series.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Add dropin test wrapper

virt test wrapper that actually runs the dropin script.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Add dropin directory

Directory that holds the dropin tests.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>