Turn the element into a FACE (or make it more like a form control)

I tried to replace a few `` in my project with this element and was thwarted by the fact that it is currently not a form control and its API is not very much like a form control. Maybe this is worth changing because it kind of _is_ an input element, and it could be everything it is now _PLUS_ a better ``? 🙃

Benefits:
- Submit via ``, integration with `FormData` etc.
- Constraint validation API integration
- API more like what developers are used to from other form controls

Downsides:
- DOM API would have to expand considerably (new attributes like `name`, `disabled`, maybe `readonly`)
- Overall a lot more complexity to hook into form lifecycle callbacks and to keep the form state in sync
- Nobody cares about forms

I like form APIs, but I understand if that's out of scope for this project.

The issue names no files, tests, or entry points. Start by reviewing the element's existing API and the platform requirements for input type="color" and form controls; determine whether submission, FormData, constraint validation, and attributes such as name, disabled, and readonly are in scope. Done requires an agreed scope and documented behavior.

Written by the indexing model from the issue text.