Make device initialisation easier by reducing required imports (#936)

Adds username and password arguments to discovery to remove the need to import Credentials.
Creates TypeAliases in Device for connection configuration classes and DeviceType.
Using the API with these changes will only require importing either Discover or Device
depending on whether using Discover.discover() or Device.connect() to 
initialize and interact with the API.

kasa/tests/test_device.py

@@ -116,13 +116,11 @@ def test_deprecated_devices(device_class, use_class):
     getattr(module, use_class.__name__)
 
 
-@pytest.mark.parametrize(
-    "exceptions_class, use_class", kasa.deprecated_exceptions.items()
-)
-def test_deprecated_exceptions(exceptions_class, use_class):
-    msg = f"{exceptions_class} is deprecated, use {use_class.__name__} instead"
+@pytest.mark.parametrize("deprecated_class, use_class", kasa.deprecated_classes.items())
+def test_deprecated_classes(deprecated_class, use_class):
+    msg = f"{deprecated_class} is deprecated, use {use_class.__name__} instead"
     with pytest.deprecated_call(match=msg):
-        getattr(kasa, exceptions_class)
+        getattr(kasa, deprecated_class)
     getattr(kasa, use_class.__name__)
 
 
@@ -266,3 +264,27 @@ async def test_deprecated_light_preset_attributes(dev: Device):
         IotLightPreset(index=0, hue=100, brightness=100, saturation=0, color_temp=0),  # type: ignore[call-arg]
         will_raise=exc,
     )
+
+
+async def test_device_type_aliases():
+    """Test that the device type aliases in Device work."""
+
+    def _mock_connect(config, *args, **kwargs):
+        mock = Mock()
+        mock.config = config
+        return mock
+
+    with patch("kasa.device_factory.connect", side_effect=_mock_connect):
+        dev = await Device.connect(
+            config=Device.Config(
+                host="127.0.0.1",
+                credentials=Device.Credentials(username="user", password="foobar"),  # noqa: S106
+                connection_type=Device.ConnectionParameters(
+                    device_family=Device.Family.SmartKasaPlug,
+                    encryption_type=Device.EncryptionType.Klap,
+                    login_version=2,
+                ),
+            )
+        )
+        assert isinstance(dev.config, DeviceConfig)
+        assert DeviceType.Dimmer == Device.Type.Dimmer