TB-1973 - CTCoreFolder.imapSession gets an unexpected NULL folderSession
TB-1973 - CTCoreFolder.imapSession gets an unexpected NULL folderSession

Call [self connect] at the start of searchUidByHeader.  This fixes a crash
if this call is the first one to be made on this folder.

tipbit/MailCore,tipbit/MailCore,tipbit/MailCore