Copy chapter PGN in study

[ErdoganSeref]

The change solves #11311 by adding a text box element below the FEN one. We use https://github.com/lichess-org/lila/blob/19bd7a0bafb87520125cd0e883467747ca67fa69/ui/analyse/src/view.ts#L134-L137 for the structure of the element. To get the PGN data we use the same technique as in https://github.com/lichess-org/pgn-viewer/blob/4019ef209acefef52b8e0b96f0c36aa51f5d0dbd/src/view/main.ts#L43-L50.