Allow bot to send notification messages

[SocksTheWolf]

This is mostly so we can beam out notifications about ScamGuard developments. It mostly just requires a command that can be executed in the tag server, and sends to the other instances.

As a bonus, it would be nice to have another version of the command that only sends to specific instances.

[SocksTheWolf]

This probably is not actually needed. Other than it being a nice to have...

[SocksTheWolf]

This could be just be another webhook that could be installed as well that pushes the bot-updates feed, would require code that installs webhooks to be more generalized.