When copying messages between mailboxes using standard IMAP, we must perform
a QUERY or FETCH in order to determine the new message UID. However, if the
server supports the UIDPLUS capability, the server will return the new UID
as part of the response to the "UID COPY" command.
This is the first of a couple modifications. We still need to fallback to a
less efficient QUERY/FETCH if the server does not support UIDPLUS.
bug 4092301
Change-Id: I9279f7fd70daf85adba3b3e202c12d67ddf91f22
284d8d7db5