Function defaultStateKeyDelegate

Default state key delegate.

Derives key as follows:

• If private chat, msg.chat.id
• If group chat, msg.chat.id + '_' + msg.sender.id
• If channel, msg.chat.id
• If non-inline callback query:
  • If in private chat (i.e. upd.chatType === 'user'), upd.user.id
  • If in group/channel/supergroup (i.e. upd.chatType !== 'user'), upd.chatId + '_' + upd.user.id