Support display of "open window" in AVM smart heaters

AVM smart heaters like Fritz!Dect 301 and Fritz!Dect 302 support a “open window” mode where the heater is turned off when a window switch detected an open window.

Apps like “BoxToGo” for Android display this value, so it is accesible through the API of AVM. However in the AVM integration for Home Assistant this seems to be missing, so there is no indication at all if a heater is in “open window” mode or not.

Screenshot of “BoxToGo” showing 5 heaters of which 2 are in “open window detected” mode:

The same heaters in Home Assistant show no indication at all, you can just see the desired temperature and mode but not the actual “open window” mode.