Prepare Image & Video loading for E2EE

Changes the urls to make sure they are decrypted, while making sure that
it is backwards compatible to libQuotient 0.6

src/messageeventmodel.cpp

@@ -54,6 +54,7 @@ QHash<int, QByteArray> MessageEventModel::roleNames() const
     roles[MimeTypeRole] = "mimeType";
     roles[FormattedBodyRole] = "formattedBody";
     roles[AuthorIdRole] = "authorId";
+    roles[MediaUrlRole] = "mediaUrl";
     return roles;
 }
 
@@ -772,6 +773,23 @@ QVariant MessageEventModel::data(const QModelIndex &idx, int role) const
         return evt.senderId();
     }
 
+    if (role == MediaUrlRole) {
+#ifdef QUOTIENT_07
+        if (auto e = eventCast<const RoomMessageEvent>(&evt)) {
+            if (!e->hasFileContent()) {
+                return QVariant();
+            }
+            if (e->content()->originalJson.contains(QStringLiteral("file")) && e->content()->originalJson["file"].toObject().contains(QStringLiteral("url"))) {
+                return m_currentRoom->makeMediaUrl(e->id(), e->content()->originalJson["file"]["url"].toString());
+            }
+            if (e->content()->originalJson.contains(QStringLiteral("url"))) {
+                return m_currentRoom->makeMediaUrl(e->id(), e->content()->originalJson["url"].toString());
+            }
+        }
+#endif
+        return m_currentRoom->urlToDownload(evt.id());
+    }
+
     return {};
 }