v0.2.0 Movin' On

This new release of dart_vlc includes:

• Addressed multiple Dart-sided memory leaks during FFI interop (@alexmercerind).
• Introduce NativeVideo for Windows to render video playback performantly (uses flutter_native_view) (@alexmercerind).
• Refactor native source code, move implementations to separate translation units & remove inline class methods (@alexmercerind).
• Fix Video rendering when explicit VideoDimensions are passed (@alexmercerind).
• Expose Player::SetHWND (@alexmercerind).
• Added showFullscreenButton to Video widget (disabled by default) (@alexmercerind).