Allow user to set custom background color on core hero block

Description of the need

For a site editor to be able to configure a front page (or any page) using the modern endless scroll design with multiple blocks that stretch the full width of the page, some of the blocks might have images others different background colors (configurable thru UI).

I would like to add this functionality into a contrib theme I am working on. Having this block in core would help (in the meantime, this is definitely contrib candidate).

Proposed solution

This could happen today if the user were able to set the background color in the existing "hero block" or had another custom block that could be used in a hero region with custom settings to control the background color.

This could be a predefined list of available colors that are included in the theme or full color support (ala color module).

A predefined list of colors would be easier - a select list of classes that would correspond to styles defined in the theme. Full color support is beyond my pay grade.

Alternatives that have been considered

https://github.com/backdrop-contrib/tatsu/issues/21

Is there a contributed module that accomplishes this? If the use case is not strong enough, I would like to see this block offered in contrib.

EDIT: This module now has a stabile Backdrop release: https://backdropcms.org/project/block_background_color

Additional information Add any other information or screenshots that would help.

I have no idea how this would work technically