Add a route reconciliation step to the host_route_sync file that uses
the BGP state table as a system of record for the routes that should or
should not be synced to the system.

In theory, kube-router should be consistently informed of route changes
via BGP Path change events that are sent to us from GoBGP. However, in
practice it seems that some routes are getting stuck in our state table.

Host route syncing is an important part of kube-router that is run in
its own goroutine, so we should be checking it for health the way we do
the major controllers to make sure that it never stops functioning.

Additionally, as the health check controller has been continuously added
on to, we also make some modifications here to make it a bit more robust
and scalable.