lib: rework LibVLC 4.0 API

Refs #27971

Supersedes !3454 (closed) and !3459 (closed)

This is draft for now, even if commits are clean. I would like to merge everything in one-shot to avoid breaking and rebreaking all LibVLC dependent CIs (libvlcpp, medialibrary, android...).

TODO:

• Add a struct callbacks for the mediaplayer
• Add a struct callbacks for the renderer discoverers
• Remove all events and event-manager
• Write a LibVLC 3.0 -> 4.0 documentation