Several form field fixes

[agjohnson]

• Wrap checkbox with correct surrounding element for a field
• Add search class to multi select dropdown to make it keyboard searchable
• Multi select label icon was not showing from missing codepoint

Screencast from 2024-01-29 23-55-21.webm

[humitos]

I'm merging this so it goes out in today's deploy.

[agjohnson]

Would this also solve the issue on the addons admin page?

Yup, this was the fix for that particular page: