feat(visitors): Visitors chat. (#2245)

* feat(visitors): Visitors chat.

For messages coming from visitors, which are not in the current room we need to supply a display name.
Mark messages with custom display name as coming from guest.

* feat: Adds a visitors version to conferenceIQ.

JitsiConferenceEventManager.js

         XMPPEvents.MESSAGE_RECEIVED,
 
         // eslint-disable-next-line max-params
-        (jid, txt, myJid, ts) => {
+        (jid, txt, myJid, ts, nick, isGuest) => {
             const id = Strophe.getResourceFromJid(jid);
 
             conference.eventEmitter.emit(
                 JitsiConferenceEvents.MESSAGE_RECEIVED,
-                id, txt, ts);
+                id, txt, ts, nick, isGuest);
         });
 
     chatRoom.addListener(

modules/xmpp/ChatRoom.js

                 this.eventEmitter.emit(XMPPEvents.PRIVATE_MESSAGE_RECEIVED,
                         from, txt, this.myroomjid, stamp);
             } else if (type === 'groupchat') {
+                const nickEl = $(msg).find('>nick');
+                let nick;
+
+                if (nickEl.length > 0) {
+                    nick = nickEl.text();
+                }
+
+                // we will fire explicitly that this is a guest(isGuest:true) to the conference
+                // informing that this is probably a message from a guest to the conference (visitor)
+                // a message with explicit name set
                 this.eventEmitter.emit(XMPPEvents.MESSAGE_RECEIVED,
-                        from, txt, this.myroomjid, stamp);
+                    from, txt, this.myroomjid, stamp, nick, Boolean(nick));
             }
         }
     }

modules/xmpp/moderator.js

                 }).up();
         }
     }
+    elem.c('property', {
+        name: 'visitors-version',
+        value: 1 }).up();
 
     return elem;
 };