When using only mass mailing two issues arise when trying to send mass
mailings containing links
* a link.tracker is created for each link to shorten; however rights are
given currently only in website_links for website designers and not to
marketing users that use mass mailing. This commit adds the rights for
link.tracker model to those people;
* a link.tracker.code is created to hold the shortened versions of the
links. As it is a technical model it is now done as superuser as rights
on link.tracked model has already been granted and adding rights on such
a technical model is not necessary;
A test is added that checks what is done with links when sending mass
mailings. It helped spotting the hereabove issue.
This commit is linked to task ID 1889703 and PR #27526.