Merging the 7.6.1 testing branch into our VTechWorks dev branch

Merge conflicts were resolved in:

item-page-title-field.component.html
  upstream heading level accessibility fix plus local customization
  to allow italics in item titles

metadata-field-wrapper.component.html
  upstream heading level accessibility fix plus local customization
  to use "Persistent Identifier" as the URI label

To fix build issues with the merged code, additional changes were made to:

angular.json - remove comment from standard JSON format file
i18n/en.json - add missing comment after label definition

The error with the missing comment appears to have occured due to a difference in opinion and/or expectations with whether the last item in a comma separated list should/does have a trailing comma.