Factor our groupMembership calculation into groupMembershipForPlayerState, since we'll be using it to also fetch the given player's player state membership too. Part of #491.
Factor our groupMembership calculation into groupMembershipForPlayerState, since we'll be using it to also fetch the given player's player state membership too. Part of #491.

jkomoros/boardgame,jkomoros/boardgame,jkomoros/boardgame