Add test for customizing also the UI labels

In relation to previous change that enabled customizing grouping labels,
add a test that allows to set those for the UI as well. Since there is
no localization support going to add possibility to define custom names
for the elements on the UI as well (this concerns mainly add report and
edit report features
Simple customization of grouping item labels

Added possibility to define labels to be used instead of the default
Release / Target profile / Test set / Product in the Add report page.
Need to check the edit report page as well.