Replaces System.Drawing with ImageSharp, and thereby fix TODO.

[bergmania]

Details

• Replaces System.Drawing with ImageSharp, and thereby fix TODO.

Test

• Go to the media section and upload files of different types.
• The following formats are supported
  • GIF : GifDecoder
  • PNG : PngDecoder
  • BMP : BmpDecoder
  • JPEG : JpegDecoder
  • TGA : TgaDecoder

[warrenbuckley]

Code changes look fine
Will need to test this out next :)

[warrenbuckley]

All works as expected

[ronaldbarendse]

While working on PR #10623, I noticed we're loading the complete image into memory (by doing Image.Load(stream)) to get the width/height. ImageSharp also has an Image.Identify(stream) method that is more efficient: https://docs.sixlabors.com/articles/imagesharp/imageformats.html#metadata-only-decoding.

The PR to update this is already done: #10964 👍🏻