TMDM-7517: implementation for portlets remove/restore/diable i18n

TMDM-7517: code refactoring and clean-ups

TMDM-7517: code refactoring - using non static methods

TMDM-7517: labels translations

TMDM-7517: final translation and UI adjustment

TMDM-7517: corrects wrong translations

TMDM-7517: add updates missed during rebase
Merge branch 'maintenance/5.6'