Broken initialization API

Since recent changes, the media library expects a SetupConfig* parameter which can contain instances of device listers, fs factories, and metadata extractor.

The issue is that some of those instances might need a pointer to the media library instance to perform their initialization. Specifically, the FS factories are often expecting a medialib instance in order to fetch a device lister (especially for the file:// one which uses the builtin one and has no other way of fetching it)

This means that the SetupConfig can't be passed to the constructor, or that a new API needs to be added in order for the FS factory to be able to fetch its device lister.