Coloured icons for signal strength sensors

[MMK21Hub]

With the 2022.12 update, my Glance cards look great thanks to the addition of colours that represent states. It would be great if sensors for Bluetooth/WiFI signal strength were also coloured red/yellow/green based on their state. The signal_strength device class already exists to facilitate this.

Since only the Mobile App integration currently displays a different icon based on the signal strength value, it would also be nice if the frontend did this automatically for signal strength sensors.

The battery device class already has both of these features implemented (icon and colour based on state).

[ChristophCaina]

in this case, I do have some more options :)

Signal Strenght (all entities that provide "dBM" as unit of measurement)

And maybe also to consider other entities that provide a percentage as Unit of measurement.
But in this case, It would be great if it could be configured if 0% is good or 100% :)

Low percentage: Good -> green

in this case, like batteries: high percentage => green