Rename the v4 file to match Elliot's [ACF field type template kit](https://github.com/elliotcondon/acf-field-type-template)
Add some of Elliot's template files, with the appropriate fields search-replaced
Merge and update the v4 field with the latest v4 template
Copy the v4 code into the v5 definition and update where appropriate (mostly belt-and-braces escaping output, as well as updating the CSS selectors to work with v5)