[DMS/ZMS] Admin Bot Improvements

[cha0sg0d]

• [x] Provides a working admin flow using the /manage command to link telegram chats with Pretix event

[cha0sg0d]

Notes on flows:

• Potential chats to link = intersection of chats where the bot is an admin and the user is an admin.

• Need to remind user to add the bot as an admin

• Admin gets asked which chat would you like to link?. Chooses chat. Then navigates to a submenu to select which events are available for linking.

• Admins can also select anonymous topic(s) from the bot as well. That's another submenu from chat selection.

Right now, links can always be overridden. Need some way to add an extra auth layer for the ability to link chats to events.

[cha0sg0d]

Notes after exploration:

• We can use dynamic menus to give the admin of list of chats.
• We can set their selected chat in a context, then proceed normally with the options to link or set an anonymous channel.

[cha0sg0d]

Notes after more exploration:

• It is significantly easier to manage chat-related things like the linked event and the anon channels from within the group.
• Managing those things outside of the group requires admins to give their Telegram login credentials to the bot.