Generalize smartdevice child support (#775)

* Initialize children's modules (and features) using the child component negotiation results
* Set device_type based on the device response
* Print out child features in cli 'state'
* Add --child option to cli 'command' to allow targeting child devices
* Guard "generic" features like rssi, ssid, etc. only to devices which have this information

Note, we do not currently perform queries on child modules so some data may not be available. At the moment, a stop-gap solution to use parent's data is used but this is not always correct; even if the device shares the same clock and cloud connectivity, it may have its own firmware updates.

kasa/cli.py

@@ -582,9 +582,14 @@ async def state(ctx, dev: Device):
     echo(f"\tPort: {dev.port}")
     echo(f"\tDevice state: {dev.is_on}")
     if dev.is_strip:
-        echo("\t[bold]== Plugs ==[/bold]")
-        for plug in dev.children:  # type: ignore
-            echo(f"\t* Socket '{plug.alias}' state: {plug.is_on} since {plug.on_since}")
+        echo("\t[bold]== Children ==[/bold]")
+        for child in dev.children:
+            echo(f"\t* {child.alias} ({child.model}, {child.device_type})")
+            for feat in child.features.values():
+                try:
+                    echo(f"\t\t{feat.name}: {feat.value}")
+                except Exception as ex:
+                    echo(f"\t\t{feat.name}: got exception (%s)" % ex)
         echo()
 
     echo("\t[bold]== Generic information ==[/bold]")
@@ -665,13 +670,22 @@ async def raw_command(ctx, dev: Device, module, command, parameters):
 @cli.command(name="command")
 @pass_dev
 @click.option("--module", required=False, help="Module for IOT protocol.")
+@click.option("--child", required=False, help="Child ID for controlling sub-devices")
 @click.argument("command")
 @click.argument("parameters", default=None, required=False)
-async def cmd_command(dev: Device, module, command, parameters):
+async def cmd_command(dev: Device, module, child, command, parameters):
     """Run a raw command on the device."""
     if parameters is not None:
         parameters = ast.literal_eval(parameters)
 
+    if child:
+        # The way child devices are accessed requires a ChildDevice to
+        # wrap the communications. Doing this properly would require creating
+        # a common interfaces for both IOT and SMART child devices.
+        # As a stop-gap solution, we perform an update instead.
+        await dev.update()
+        dev = dev.get_child_device(child)
+
     if isinstance(dev, IotDevice):
         res = await dev._query_helper(module, command, parameters)
     elif isinstance(dev, SmartDevice):