HCP Link Status (#16959)

* adds LinkStatus component to NavHeader to display banner with HCP link status

* adds changelog entry

* adds period to connected status message

* updates hcp link status to current cluster polling to automatically update state

ui/app/models/node.js

@@ -24,6 +24,7 @@ export default Model.extend({
   version: attr('string'),
   type: attr('string'),
   storageType: attr('string'),
+  hcpLinkStatus: attr('string'),
 
   //https://www.vaultproject.io/docs/http/sys-leader.html
   haEnabled: attr('boolean'),