Before: A pointer to the favicon gets written in the BookmarkMatch and using this pointer the icon gets created when the Plasma::QueryMatch gets created.
Now: Using the favicon pointer the icon gets created and written to the BookmarkMatch, when the QueryMatch is created the icon value is read.
This makes the code easier to unserstand and the BookmarkMatch is independent of the Favicon class.
Depends on D28196, because this bugfix is needed for my config.