tests/kms_chamelium: add a link-status test

This test first checks that on normal hotplug, the link-status property is set
to GOOD. It then triggers a link failure, checks that the property is updated
to BAD. Checks are performed to make sure the new mode list is a subset of the
previous one. After that, a new modeset is performed if necessary and the
link-status property is set back to GOOD.

This whole dance is repeated until we reach fallback modes.

Signed-off-by: Simon Ser <simon.ser@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>