Simplify CONDSTORE/non-CONDSTORE code paths.

Horde_Imap_Client already does the abstraction for us.

Also save the total amount of messages in an IMAP folder
for all server types again, it's not worth the effort / complexity
to create seperate code paths for this.

Request: 12597
Missed a place to re-add $status['messages']
$condstore doesn't exist anymore, use $modseq
Log the modseq used for IMAP collections.