Add support for sub areas

Within an area, we should be able to create sub areas. For example, a great room could include a dinning area, a living area, and a entertainment area. My main reason for wanting this is so that there will be a standard way for MMWave sensors to see the house. Many seem to have the ability to create sensing areas. It would be nice if these could be defined and used in Home Assistant.

Others will want to be able to assign entities and devices to sub areas. I think that makes sense, also.

Could use labels for that.

It may be interesting to implement a sub areas or secondary area feature… Let me explain.

For example I have the HP printers integration… The printer is located at our Home Office, but I don’t want that HP printer integration overpopulates Home Office card. For now, I’ve created a Printer area, but that’s not what I wanted or needed.

The request is a sub areas feature, which can be con figured inside an area and be displayed in a collapsed sub card to avoid overpopulation of sensors inside an area.

Thanks in advance