Fix compilation with VLCKitv4
This depends on VLCKit!214 (merged) and VLCKit!215 (merged) as well as !838 (merged). It allows compilation of the VLC-iOS and VLC-tvOS apps both with VLCKitv3 and v4.
This MR merely adds compilation support and minor optimizations. There is more work to be done to make full use of the v4 API improvements.
Edited by Felix Paul Kühne