custom_card_esh_room: add support for window states

[dominikheinz]

Is your enhancement request related to a problem? Please describe. Currently, the custom room card allows for states of lights or thermostates in a room. However, there is no option to see the state of all the windows opened in a room. I can see this being very useful, when e.g. leaving the house, and wanting to quickly check if there are any windows left open in any of the rooms. Also, having sensors on windows/doors to indicate the open/closed state is pretty common in many smarthome setups. Thoughts?

Pinging @EverythingSmartHome @mpeterson @rensknoors since you guys are listed as the authors :)

Describe the solution you'd like Add an additional icon to indicate the state of a window group (e.g. open/closed). In similar fashion to the light group, add variables for the icons. For defaults, I would suggest:

• https://pictogrammers.com/library/mdi/icon/window-closed/
• https://pictogrammers.com/library/mdi/icon/window-open/ Also, it might make sense to add a variable to set a custom color the card should use when the window state is open/closed.

Describe alternatives you've considered

Additional context