Add factory-reset command to cli (#1108)

Allow reseting devices to factory settings using the cli: `kasa device factory-reset`.

kasa/cli/device.py

@@ -166,6 +166,17 @@ async def reboot(plug, delay):
     return await plug.reboot(delay)
 
 
+@device.command()
+@pass_dev
+async def factory_reset(plug):
+    """Reset device to factory settings."""
+    click.confirm(
+        "Do you really want to reset the device to factory settings?", abort=True
+    )
+
+    return await plug.factory_reset()
+
+
 @device.command()
 @pass_dev
 @click.option(