Backed enums for card attributes

[Jonas-johansen]

It would be great if card attributes supported backed enums or allowed formatting via a formatStateUsing method.

Use case:
I'm currently using a card attribute based on a backed enum. In the layout, it displays the raw enum value, but ideally, it should render the label via Filament's ->getLabel() method. Even better would be support for dynamic colors using ->getColor().