Refactor in VLC 4.0 removed the libvlc_instance_t parameter to most functions from libvlc_media_t (in particular constructor) and only kept it for preparsing/thumbnailing requests.
This MR uses this beginning to remove some parameters, and then removes more code by simplifying even more the initializers.
A bigger impact change is the one adding the selector preparseWithOptions:timeout:library: allowing the user to provide its own VLCLibrary object to configure the preparsing options.