Autosearch

Make the user search automatically. This includes a timer to ensure that we aren't constantly pinging the server as the user types, the search is started 0.5s after the user stops typing. The `PublicRoomListModel` is upgraded to work in the same manner as it was architected slightly differently.

src/models/userdirectorylistmodel.cpp

@@ -59,6 +59,12 @@ void UserDirectoryListModel::setSearchText(const QString &value)
     m_searchText = value;
     Q_EMIT searchTextChanged();
 
+    if (m_job) {
+        m_job->abandon();
+        m_job = nullptr;
+        Q_EMIT searchingChanged();
+    }
+
     attempted = false;
 }