Change state_information to return feature values (#804)

This changes `state_information` to return the names and values of
all defined features.
It was originally a "temporary" hack to show some extra, device-specific
information in the cli tool, but now that we have device-defined
features we can leverage them.

kasa/smart/smartdevice.py

@@ -334,15 +334,6 @@ class SmartDevice(Device):
         ssid = base64.b64decode(ssid).decode() if ssid else "No SSID"
         return ssid
 
-    @property
-    def state_information(self) -> Dict[str, Any]:
-        """Return the key state information."""
-        return {
-            "overheated": self._info.get("overheated"),
-            "signal_level": self._info.get("signal_level"),
-            "SSID": self.ssid,
-        }
-
     @property
     def has_emeter(self) -> bool:
         """Return if the device has emeter."""