GameKit iOS 14.5 to 15.0 API Differences

GKError.h
Added GKErrorFriendRequestNotAvailable
GKGameCenterViewController.h
Added GKGameCenterViewControllerStateLocalPlayerFriendsList
GKLocalPlayer.h
Added GKLocalPlayer.isPresentingFriendRequestViewController
Added -[GKLocalPlayer presentFriendRequestCreatorFromViewController:error:]
GKMatchmakerViewController.h
Added GKMatchmakingModeInviteOnly
Added GKMatchmakerViewController.canStartWithMinimumPlayers
GKTurnBasedMatchmakerViewController.h
Added GKTurnBasedMatchmakerViewController.matchmakingMode