Refactor and fix invitations

-Move invitation handling into RoomPage and delete InvitationPage
-Open the new room after accepting the invitation

src/neochatroom.cpp

@@ -75,6 +75,12 @@ NeoChatRoom::NeoChatRoom(Connection *connection, QString roomId, JoinState joinS
     connect(this, &Room::aboutToAddHistoricalMessages, this, &NeoChatRoom::readMarkerLoadedChanged);
 
     connect(this, &Quotient::Room::eventsHistoryJobChanged, this, &NeoChatRoom::lastActiveTimeChanged);
+
+    connect(this, &Room::joinStateChanged, this, [=](JoinState oldState, JoinState newState) {
+        if(oldState == JoinState::Invite && newState != JoinState::Invite) {
+            Q_EMIT isInviteChanged();
+        }
+    });
 }
 
 void NeoChatRoom::uploadFile(const QUrl &url, const QString &body)
@@ -685,3 +691,8 @@ bool NeoChatRoom::readMarkerLoaded() const
     const auto it = findInTimeline(readMarkerEventId());
     return it != timelineEdge();
 }
+
+bool NeoChatRoom::isInvite() const
+{
+    return joinState() == JoinState::Invite;
+}