MDL-40356 lib: Added a new setting to display more information from the fullname function.
MDL-40356 lib: Unit tests for the alternativefullnameformat setting.
MDL-46921 lib: Add sorting on additional name fields

A thank you to Yishe Choden for creating a patch for this issue.
MDL-46921 lib: Update to the get_all_user_name_fields() function and unit tests.
MDL-46921 lib: Allow sorting on additional fields admin and enrolment pages.