Detect offline hub children and fail fast on writes to them (#1830)

Hubs keep reporting for children they have lost contact with, so callers
see stale values as if they were live. Trying to write to such devices
fail after timeouts with a generic error.
This PR exposes the offline/online information as reported by the hub,
and refuses writes to unreachable child devices without waiting for
device errors.

In details:
- Add new API: `Device.is_available`; hub children report unavailable
when the hub marks them offline or no longer lists them.
- New feature `available` for child devices to make it visible to the
CLI.
- Refuse writes to unavailable children with the new
`DeviceUnavailableError` instead of waiting for the hub to time out.

kasa/smart/smartdevice.py

@@ -730,7 +730,7 @@ class SmartDevice(Device):
 
         See :meth:`is_on`.
         """
-        return await self.protocol.query({"set_device_info": {"device_on": on}})
+        return await self._query_helper("set_device_info", {"device_on": on})
 
     async def turn_on(self, **kwargs: Any) -> dict:
         """Turn on the device."""
@@ -833,8 +833,8 @@ class SmartDevice(Device):
 
     async def set_alias(self, alias: str) -> dict:
         """Set the device name (alias)."""
-        return await self.protocol.query(
-            {"set_device_info": {"nickname": base64.b64encode(alias.encode()).decode()}}
+        return await self._query_helper(
+            "set_device_info", {"nickname": base64.b64encode(alias.encode()).decode()}
         )
 
     async def reboot(self, delay: int = 1) -> None:
@@ -843,14 +843,14 @@ class SmartDevice(Device):
         Note that giving a delay of zero causes this to block,
         as the device reboots immediately without responding to the call.
         """
-        await self.protocol.query({"device_reboot": {"delay": delay}})
+        await self._query_helper("device_reboot", {"delay": delay})
 
     async def factory_reset(self) -> None:
         """Reset device back to factory settings.
 
         Note, this does not downgrade the firmware.
         """
-        await self.protocol.query("device_reset")
+        await self._query_helper("device_reset")
 
     @property
     def device_type(self) -> DeviceType: