LB-564: Chained-blog setting should be on livedesk level.
* an attempt
LB-564: Chained-blog setting should be on livedesk level.
* done
LB-610: Blog Provider can't be deleted when it's used in another liveblog
* start of an rewriting on chained blogs
LB-509: Chained Blogs - On provider delete the chained blogs are not deleted

Fetch Source Id so that source can be unchained without reloading.