i18n: clean-up ui-generic-messages.
ui-generic-messages has generated keys - maybe from older version of key.generators - which seem obsolete. some of them maybe still required... ;-|

Restore the "i18n awareness" between the layout primitives like tabs, fields and dialog itself.

It used to be that you could have a set of generic keys that would apply without having to be so specific. Now it seems you cannot escape recreating keys which share common values. The way the segments apply seems to have become more rigid.