func NewKeyPolicy(config *goodkey.Config, bkc BlockedKeyCheckFunc) (goodkey.KeyPolicy, error)
NewKeyPolicy returns a KeyPolicy that uses a sa.BlockedKey method. See goodkey.NewKeyPolicy for more details about the policy itself.
BlockedKeyCheckFunc is used to pass in the sa.BlockedKey method to KeyPolicy, rather than storing a full sa.SQLStorageAuthority. This makes testing significantly simpler.
type BlockedKeyCheckFunc func(context.Context, *sapb.KeyBlockedRequest, ...grpc.CallOption) (*sapb.Exists, error)