Add a feature to copy sticker packs

[Lekrixsss]

Add a command, for example /copy [STICKER_SET] to make a copy of any sticker pack

[zeroone2numeral2]

To do this the bot would have to:

1. fetch the sticker pack and its content
2. create a new set
3. for every sticker in the pack we want to copy, send an addStickerToSet request to Telegram

This would be too time consuming for the bot, and will very easily result in rate-limiting from the server. To execute this kind of long-running commands that require many network requests, I would have to introduce a jobs queue that can execute this tasks asynchronously and gracefully handle the rate limiting. I believe I won't be able to work on this task anytime soon, I'm labeling as "help wanted" in case anyone wants to work on this but it's very unlikely to happen