Add extract frame sample to libvlcsharp-samples
Problem to solve
Add sample for users looking to extract frames
Intended users
new users looking to extract frames
Proposal
Extract and adapt https://github.com/ZeBobo5/Vlc.DotNet/blob/develop/src/Vlc.DotNet.Wpf/VlcVideoSourceProvider.cs
Documentation
Add it to libvlcsharp-samples repo