Update Imap.ClientSession now IMAP NO commands aren't treated as errors

Check the response code when logging in for the command, and handle as
appropriate.
5 jobs for wip/156-mailbox-not-exist in 55 minutes and 34 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #259403
fedora

00:10:43

passed #259404
ubuntu

00:13:54

 
  Test
passed #259405
flatpak

00:39:47

 
  Deploy
passed #259406
review

00:00:25

passed #259407
allowed to fail manual
stop_review

00:01:26