Expose template functions to retrieve icon from areas, devices and entities

[dinhani]

Describe the enhancement

I would like to have functions like area_icon, device_icon and entity_icon available in templates to retrieve the icon name defined in these components.

Example usage

When:
the stove icon is defined for the Kitchen area

Using:
{{ area_icon('kitchen') }}

Would output:
mdi:stove

Current workarounds

Usually I created a dictionary inside the template mapping area names to the icons I want to use (the same defined in the official registry).

Anything else?

It seems this information is already available in the same entitities that functions like area_name, device_name and entity_name uses to return these values, so maybe it is just creating the helper functions and exposing them to Jinja?