Feature Request: Add an icon option to attribute row type in entities card

[tomlut]

The schema for attributes as rows in entities cards does not currently support an icon option see erroneously opened issue: #9461

I humbly request that it be added.

An older card I made before this schema test was introduced actually works (displays the correct icons), however it does generate a lot of errors when the card is opened for editing.

I can help by updating the documentation if you like.

[mbo18]

I vote for! I have a card that was working fine with icon: but I needed to update it and now I'm unable to add icon: back...

[spacegaier]

I created a PR to tackle that: #9963