Intake email reply

Intakes are perfect way to collect requests directly from email. However there is no way to keep client updated since we cannot reply to intakes created by email.

Solution would be to reply from Plane directly:

1. Attach signature from commenter profile
2. Setup own smtp server for replies
3. Add mutiple SMTP servers for replying from various address
4. Keep the thread so when client replies to email address it is sent from it will go to Plane even if address is not intake email

This solution is already added by Linear so their way can be inspiration.