Refactor VideoPlayerController initialization to adhere to video_player ^2.8.2 guidelines

[ishworpanta10]

Updated VideoPlayerController initialization to use VideoPlayerController.networkUrl(Uri.parse('video_url')), complying with video_player ^2.8.2 guidelines.

Changes :

final videoPlayerController = VideoPlayerController.network(
    'https://flutter.github.io/assets-for-api-docs/assets/videos/butterfly.mp4'); 
   
   To 
   
   final videoPlayerController = VideoPlayerController.networkUrl(Uri.parse(
    'https://flutter.github.io/assets-for-api-docs/assets/videos/butterfly.mp4'));