Both tracker-miner-fs and tracker-extract will use TrackerModuleManager
infrastructure to find the graph where a file's nie:InformationElement
belongs to. All data from tracker-extract will be dumped in the same
graph.

For nie:DataObjects, and supporting nie:InformationElements created for
files that do not have an extractor (eg. nfo:Folder), we will use the
tracker:FileSystem graph.

This makes all filesystem data in tracker:FileSystem, and all extracted
metadata in the other graphs, as specified by extract modules.