Messages would get duplicated when you chat with yourself, worse if you
had omemo enabled the duplicated message would say something along the
lines of "Your client doesn't support OMEMO". The cause was carbons
when the message was sent from another client, whilst it was a sent
and received message when profanity was the one to send it. This commit
ignores the carbon message in the 1st case and ignores the received one
in the 2nd.
Fixes https://github.com/profanity-im/profanity/issues/1595
91e8a89b59