Replace table tags for color palettes on user profile screen

[sabernhardt]

To avoid the semantics of tables, the color palettes' table tags can be replaced with generic div tags.

[desrosj]

This seems like it would be fine. I can't think of any backwards compatibility issues here unless someone is targeting the color palette tables to style them differently. But I think that's a long shot.

Moving to Future Release for now and can revisit after FSE in 5.8.

[joedolson]

At minimum, these should have role="presentation", but I can't see any good reason not to replace these. This is also an accessibility issue, since it's a misrepresentation of the information in tabular format, though that's relatively minor.

• Replaces table elements.
• Adds a .color-palette-shade class to the inner div elements.
• Updates styles to fit the new elements.

Trac 53157

[sabernhardt]

Of the ​plugins that target the `.color-palette` class, a few include table or td elements. However, among the ​plugins I was able to check, the change seems to have few/minor effects.

1. WP Dark Mode would need to update the script that targets the table for its color adjustments.
2. Hide My WP Ghost has a copy of core styles and scripts for the login page. If the plugin also enqueues those copies within the admin, the files would require updating.