[Feature] Convert Window Cover into Window Accessory 
**Problem description**
I have a Zigbee window motor by aquara (SRSC-M01) in my office, I've set it up with Zigbee2mqtt and z2m, and it works fine, however there is a caveat, the window is exposed as a window cover to home kit, and in my case the device is not a cover, it is the window it self.

**Suggested solution**
Lookin at the [Plugin Configuration Page](https://z2m.dev/config.html) there is a section that talks about converters, and altho it mentions window covers, it doesn't seem to expose any window conversion options that I could find. My guess is that that would  be the cleanest solution and in line with the current way the plugin works. 

**Describe alternatives you've considered**
I've considered using the [MQTT-Thing Plugin](https://github.com/arachnetech/homebridge-mqttthing#readme), tapping into the Zigbee2mqtt topics, and altho I managed to get a window accessory working there, I was faced with what seems to be a bug  in the Plugin https://github.com/arachnetech/homebridge-mqttthing/issues/572 but even then, I think this should be present in z2m directly.

**Additional context**
Considering how HomeKit treats Window accessories differently security wise, I would think this is a very important feature. Because in my case, and I assume others, my window needs to have the same security level as doors or garage gates for example, and currently home kit treats it as a climate accessory.

**Are you willing to contribute to this feature?**
I would, but I'm not familiar with the project structure, but willing to give any additional help I could give on the subject.
