Ubuntu: adds an secure connection option selector to Imap Settings

User can select connection type from an expandable option selector,
which updates the imapPort text field to the standard connection port.

User can still override port value in imapPort text field

Also we have to use QT_TR_NOOP for marking strings in list model
elements for translation and call translate on them in the
selectorDelegate. QT_TR_NOOP apparently makes the strings visible to
Qt Linguist but doesn't actually translate anything.

REVIEW: 117212