Refactoring direct channel creation to use transaction to avaoid state where channel is created without both users

store/store.go

@@ -54,6 +54,7 @@ type TeamStore interface {
 
 type ChannelStore interface {
 	Save(channel *model.Channel) StoreChannel
+	SaveDirectChannel(channel *model.Channel, member1 *model.ChannelMember, member2 *model.ChannelMember) StoreChannel
 	Update(channel *model.Channel) StoreChannel
 	Get(id string) StoreChannel
 	Delete(channelId string, time int64) StoreChannel