Make get_module return typed module (#892)

Passing in a string still works and returns either `IotModule` or
`SmartModule` type when called on `IotDevice` or `SmartDevice`
respectively. When calling on `Device` will return `Module` type.

Passing in a module type is then typed to that module, i.e.:
```py
smartdev.get_module(FanModule)  # type is FanModule
smartdev.get_module("FanModule")  # type is SmartModule
```
Only thing this doesn't do is check that you can't pass an `IotModule`
to a `SmartDevice.get_module()`. However there is a runtime check which
will return null if the passed `ModuleType` is not a subclass of
`SmartModule`.

Many thanks to @cdce8p for helping with this.

kasa/tests/test_iotdevice.py

@@ -19,7 +19,7 @@ from voluptuous import (
 from kasa import KasaException
 from kasa.iot import IotDevice
 
-from .conftest import handle_turn_on, turn_on
+from .conftest import get_device_for_fixture_protocol, handle_turn_on, turn_on
 from .device_fixtures import device_iot, has_emeter_iot, no_emeter_iot
 from .fakeprotocol_iot import FakeIotProtocol
 
@@ -258,3 +258,30 @@ async def test_modules_not_supported(dev: IotDevice):
     await dev.update()
     for module in dev.modules.values():
         assert module.is_supported is not None
+
+
+async def test_get_modules():
+    """Test get_modules for child and parent modules."""
+    dummy_device = await get_device_for_fixture_protocol(
+        "HS100(US)_2.0_1.5.6.json", "IOT"
+    )
+    from kasa.iot.modules import Cloud
+    from kasa.smart.modules import CloudModule
+
+    # Modules on device
+    module = dummy_device.get_module("Cloud")
+    assert module
+    assert module._device == dummy_device
+    assert isinstance(module, Cloud)
+
+    module = dummy_device.get_module(Cloud)
+    assert module
+    assert module._device == dummy_device
+    assert isinstance(module, Cloud)
+
+    # Invalid modules
+    module = dummy_device.get_module("DummyModule")
+    assert module is None
+
+    module = dummy_device.get_module(CloudModule)
+    assert module is None