Add ability to define color for Repeater items like for Repeater Matrix items

[ivangretsky]

Short description of the enhancement

We now have the ability to define the color of Repeater Matrix item label (per type) putting color code in corresponding option field. I wish we could do the so for regular repeaters. I need this to style nested repeaters in line with their parent Repeater Matrix types.

[szabeszg]

I'd like to add that as far as I can tell the color definition feature of Repeater Matrix items is "half baked", see:
https://processwire.com/talk/topic/27043-weekly-update-%E2%80%93-22-april-2022/?do=findComment&comment=223564
So far, no one has confirmed this behavior I reported, so it might be me who is doing something wrong.

Note that Jonathan Lahijani shared his way of coloring them and that is also what I use for the time being:
#440 (comment)