This refactors the v1 lease controller. It makes two functional differences
to the lease controller:
* It no longer ties lease updates to node pings or node status updates
* There is no fallback mechanism to status updates
This also moves vk_envtest, allowing for future brown-box testing of the
lease controller with envtest
This allows users who have a shared informer that is *not* filtering on
node name to supply a filter for event handlers to ensure events do not
fire for pods not scheduled to the node.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
