Add HA/LB endpoints for kube-apiserver

* Add HA docs for API server.
* Add auto-evaluated internal endpoints and clarify the loadbalancer_apiserver
vars and usecases.
* Use facts for kube_apiserver to not repeat code and enable LB endpoints use.
* Use /healthz check for the wait-for apiserver.
* Use the single endpoint for kubelet instead of the list of apiservers
* Specify kube_apiserver_count to for HA layout

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

roles/kubernetes/master/templates/manifests/kube-scheduler.manifest.j2

@@ -12,7 +12,7 @@ spec:
     - /hyperkube
     - scheduler
     - --leader-elect=true
-    - --master=http://127.0.0.1:{{kube_apiserver_insecure_port}}
+    - --master={{ kube_apiserver_endpoint }}
     - --v={{ kube_log_level | default('2') }}
     livenessProbe:
       httpGet: