When forwarding emails into the group inbox, we now use the
original sender email as the from_address since
2ac9fd9dff. However, we have not
been saving the original CC addresses of the forwarded email,
which are needed to include those recipients in on the conversation
when replying via the group inbox.
This commit captures the CC addresses on the incoming email, and
makes sure the emails are created as staged users and added to the
list of topic allowed users so they are included on CC's sent by
the GroupSmtpEmail and other jobs.
9f36d8ad43