Show health details (eg, healthy, unhealthy, initial, ...) for instances
that are attached to an application load balancer. This was relatively
low-hanging fruit because I already had the information available but
was throwing it away on the backend. This includes both the change to
the resource to make this happen and the change to the front-end to
visualize it. Ideally.

Adds an additional endpoint to get the health status of instances which
are attached to a classic load balancer. We can probably just use this
request to list the instances in general, rather than trying to merge
the results of the list that we grab from the `/{elbName}` endpoint with
this one.

Add display of instance health status for instances which are listening
to classic load balancers.