Add select focus state in legacy edge

[spencercanner]

Problem

• Legacy Edge does not inherit and user agent focus styles when a select element's appearance has been changed to none. This results in the select elements not having a visible focus state in that browser.
• It is also missing a focus state in high contrast mode

Solution

• Move borders from the parent div to the select element, so they can be updated when the select element is focused
• Browsers should still inherit their user agent focus styles and have those applied on top of the darkened border
• The :focus-within selector could be used to update the parent's border colour when the child select is focused, but it is not supported in IE11 or legacy Edge
• Add an outline to the select element when it is focused in high contrast mode

To 🎩 :

• Verify that the default and focus styles of the select elements look the same as before this change
• In legacy edge, verify that the focus state is visible by a darkening of the border
• In high contrast mode, verify that the focus state is visible with a thicker outline

Windows:

• Legacy Edge 18
• Legacy Edge 17
• Chromium Edge 86
• Chromium Edge 85
• Firefox 82
• Firefox 81
• Chrome 86
• Chrome 85
• Opera 72
• Opera 71
• IE11
• High contrast mode - Legacy Edge 18

Mac:

• Safari 13
• Safari 12
• Safari 8
• Firefox 82
• Firefox 81
• Chrome 86
• Chrome 85
• Chromium Edge 86
• Chromium Edge 85
• Opera 72
• Opera 71

iOS:

• Safari
• Chrome

Android:

• Chrome
• Firefox
• Samsung Internet