Issue #3239705 "Add the ability to sort links via Views by using _views_data_alter in a link.views.inc file to enable the ability to sort"

When the Link field was ported into Core for 8.x the ability to add 'click sortable' under a views table was not added. This adds it through a link.views.inc file that uses _views_data_alter. This may not be the most recent way of doing things as there are no other core modules using a module.views.inc but this is a working solution and many contrib modules utilize it still. The tests don't test views sort functionality because the links module doesn't provide any sort functionality itself and this is a function of views. No other core fields have 'click sortable' tested under their module tests.