premoves+promotion bug

[gbtami]

blunderman1 reportde on Discord:
"Here is a bug report: I thought I meessed up something when adapting the relevant code for bughouse, but it seems behavrior is the same with regular variants as well. When doing premoves+promotion, promotion options are not rendered until it is the player's turn, which defeats the purpse of doing a premove. Tested with regular chess variant"