Import KStatusBarOfflineIndicator from KIO
Summary:
KTorrent is the only user of this class and it doesn't really belong into KIO. Importing it here will allow to get rid of it in KIO.
See T12373
Reviewers: guisson, stikonas, shaforostoff
Reviewed By: stikonas
Maniphest Tasks: T12373
Differential Revision: https://phabricator.kde.org/D26411