Allow some countries to be the first options in the list

Problem/Motivation

Country lists are long and can be difficult to work with.

It can be an improvement if a couple of often selected countries are shown as the first options in the select list.

For example in a Dutch website that ships products to neighbouring countries Belgium and Germany, it could list these countries first.

Proposed resolution

- provide a UI to select countries that should be listed first
- sort countries in the widget showing the selected countries first

User interface changes

- sorting of the options