FS-9683: Pass call recovery status to Verto

Previously, users implementing a Verto workflow where both user login and
placing a new call are automated (eg., visiting a URL, and the videoconference
loads automatically) faced the challenge of not having a reliable way to know
that a page load will result in Verto's call recovery mechanism reconnecting
an existing detached call or not.

This adds a verto.clientReady JSON-RPC message, emitted after all calls are
re-attached, which contains a 'reattached_sessions' array, containing the
sess_id of any reattached session.

Client side, this can be caught in the onMessage handler, under the
$.verto.enum.message.clientReady key.

html5/verto/verto_communicator/src/vertoService/services/vertoService.js

@@ -632,6 +632,11 @@ vertoService.service('verto', ['$rootScope', '$cookieStore', '$location', 'stora
               case $.verto.enum.message.display:
                     $rootScope.$apply(function() {});
                     break;
+              case $.verto.enum.message.clientReady:
+                    $rootScope.$emit('clientReady', {
+                      reattached_sessions: params.reattached_sessions,
+                    });
+                    break;
               default:
                 console.warn('Got a not implemented message:', msg, dialog, params);
                 break;