feat(ui): Color Picker V2

[hipsterusername]

Summary

This adds new features to the color picker:

• Ability to pin the color picker into the top left corner of the canvas.
• Hex/RGB switch for the color picker
• Cleaner visibility of the FG/BG toggle.

Related Issues / Discussions

Discord asks.

QA Instructions

Pin it. Unpin it. Hex it. Bop it.

Merge Plan

Merge away.

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[lstein]

This is a definite improvement over the current color picker and I'm going to approve it, but here are some ideas for future improvements:

1. When unpinned, the color picker does not offer a visible foreground/background switch UI element. Users have to know to use the "x" hotkey (this is current color picker behavior as well). The new switch icon should appear in the colorpicker titlebar regardless of whether it is pinned or not.
2. When unpinning the pinned picker, it simply disappears. It would be more natural for it to return to its unpinned position.
3. In the unpinned state, the color picker is unmovable. It is pinned to a fixed position in the browser window. It would be more natural for the unpinned picker to be movable by dragging, turning it into a floating window.