Add functionality to export the forward game's PGN

[ZeliTheZealot]

Sometimes we might want to be able to play the game forwards from another chess website, but they require a PGN which is not trivial to get from the reverse solution on Retractor. Can we get a functionality to do this please?

For example when solving this puzzle I used Retractor but for a general audience they understand the forward game better. I'd love to attach a forward game where the reader can just click a link (e.g. LiChess) to view it.