UBERF-9605: Test MTA hook integration

[ArtyomSavchenko]

Add service that should handle MTA hook request from SMTP server, it should replace Cloudflare Email Worker for inbound emails

[aonnikov]

hook name is too generic per my point of view, is it for email?

[ArtyomSavchenko]

hook name is too generic per my point of view, is it for email?

I think this service can be used for several integrations, for example, mail, telegram, slack.
From my point of view this service should only send event into the queue with corresponding topic:

• mail hook -> mail topic
• telegram hook -> telegram topic
  etc.