Add HA/LB endpoints for kube-apiserver

* Add auto-evaluated internal endpoints and clarify the loadbalancer_apiserver
vars and usecases.
* Add loadbalancer_apiserver_localhost (default false). If enabled, override
the external LB and expect localhost:443/8080 to be new internal only frontends.
* Add kube_apiserver_multiaccess to ignore loadbalancers, and make clients
to access the apiservers as a comma-separated list of access_ip/ip/ansible ip
(a default mode). When disabled, allow clients to use the given loadbalancers.
* Define connections security mode for kube controllers, schedulers, proxies.
It is insecure be default, which is the current deployment choice.
* Rework the groups['kube-master'][0] hardcode defining the apiserver
endpoints.
* Improve grouping of vars and add facts for kube_apiserver.
* Define kube_apiserver_insecure_bind_address as a fact, add more
facts for ease of use.

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

roles/kubernetes/master/templates/kubectl-kubeconfig.yaml.j2

@@ -5,7 +5,7 @@ preferences: {}
 clusters:
 - cluster:
     certificate-authority-data: {{ kube_node_cert|b64encode }}
-    server: https://{{ groups['kube-master'][0] }}:{{ kube_apiserver_port }}
+    server: {{ kube_apiserver_endpoint }}
   name: {{ cluster_name }}
 contexts:
 - context: