Add icon_color to New Heading entity badges

[Mariusthvdb]

As a place holder, it would be great if icon_color would be supported in the new Heading cards.

Ive tried a single entity, which is colorized in the entity picker for the Heading:

but the heading displays without color:

Ofc, this would also be applicable for the main resource, custom-ui itself, and not only for custom-icon-color