Color picker popover UI

[JoryHogeveen]

Description

This PR converts the color picker field into a popover color picker using the Dropdown WP react component.

Related GitHub issue(s)

Fixes #6858

Testing instructions

1. Create color field (single and repeatable)
2. See current UI
3. Rebuild DFV with the changes in this PR
4. See new UI :)

Screenshots / screencast

v2.9.1:

Suggestion: Newer UI suggesion:

Changelog text for these changes

PR checklist

• [x] I have tested my own code to confirm it works as I intended.
• [x] My code follows the WordPress Coding Standards.
• [x] My code follows the WordPress Inline Documentation Standards.