Change the order of variables on a dashboard

[AlirieGray]

As a user
With editor permissions or higher
When I am viewing the list of variables at the top of the dashboard page
Then I would like to be able to change the order of variables as they appear in that list

This order should be persisted, so that I see the variables in the same order when I close and return to the dashboard page

[AlirieGray]

Depends on: #12375