Packaging and configuration support for EDU licence

As part of the new EDU-licence enablement in CI and RTA, also packaging and configuration need to be enhanced. This ticket tracks that activity.

As all LTS Qt versions are included, the EDU-licence needs to be configured in all the respective repositories. Additionally, as the installer needs to be able to support EDU-licence also, there is related backend and packaging work.

Please see the related EDU-epic for more details.