Add basic support, no extra features, for 26.1.2; should work as before.

This was sped up by helpful pull requests which also contributed to adding redirect following for URLs.

In addition, I know that most people probably don't use it, but picking the map from an image in creative mode should now "work" on Paper. However, Paper does some odd stuff with maps, so you'll get a blank map at first and after a server restart it will show the image. This is isolated to Paper and it works shows right away like would be expected on Spigot.