Allow 'away' filter on person/device_tracker entities

[Mariusthvdb]

with device_classes we have state coloring. it shows the state looking at the color, in the Frontend dashboard, And in more-info.

however, on person entities this is not the case.

we can set card_mod filter to those, with

card_mod:
  style:
    hui-generic-entity-row:
      $: |
        state-badge {
          filter: {{'grayscale(100%)' if not is_state(config.entity,'home')
                    else 'none'}};
        }

but it requires us to do that on each individual person entity used in the cards.
Besides that, it does Not apply to more-info, where we can not set a card mod.
Or automatic Maps (well, we can set those manually, but again , a lot of extra work)
Or see a group (legacy style) with person entities, dropping down in more-info in full color....

Which makes for a very confusing interface, because those pictures are very prominent and tend to give the wrong impression.

it would be so nice if HA Dashboard could set this for us. by design. Maybe allow manipulating that by means of the state_color: true option.

id be willing to have a go at Pr'ing this, but it seems less straightforward than adding a device_class color, so if agreed please help.

thanks for considering