Add ability to freeze animated images (GIFs) at first frame

[wosika]

Summary

• Added animate parameter to control animation playback for animated images (like GIFs)
• When animate is set to false, only the first frame is displayed

Implementation details

• Added animate boolean parameter to all ExtendedImage constructors (default: true)
• Modified _handleImageFrame method to ignore subsequent frames when animate is false
• This allows developers to display animated images as static images when needed

 void _handleImageFrame(ImageInfo imageInfo, bool synchronousCall) {
  // If animation is disabled and we already have the first frame, ignore subsequent frames
  if (!widget.animate && _frameNumber != null && _frameNumber! >= 0) {
    return;
  }
  ...
}

Usage

  ExtendedImage.network(
    'your_gif_url.gif',
    animate: false,  // Freezes the GIF at first frame
  )