Move connect_single to SmartDevice.connect (#538)

This refactors `Discover.connect_single` by moving device instance construction into a separate device factory module.
New `SmartDevice.connect(host, *, port, timeout, credentials, device_type)` class method replaces the functionality of `connect_single`,
and also now allows constructing device instances without relying on UDP discovery for type discovery if `device_type` parameter is set.

---------

Co-authored-by: Teemu R. <tpr@iki.fi>

kasa/tests/test_smartdevice.py

@@ -1,12 +1,12 @@
 import inspect
 from datetime import datetime
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 import pytest  # type: ignore # https://github.com/pytest-dev/pytest/issues/3342
 
 import kasa
 from kasa import Credentials, SmartDevice, SmartDeviceException
-from kasa.smartstrip import SmartStripPlug
+from kasa.smartdevice import DeviceType
 
 from .conftest import handle_turn_on, has_emeter, no_emeter, turn_on
 from .newfakes import PLUG_SCHEMA, TZ_SCHEMA, FakeTransportProtocol
@@ -215,6 +215,28 @@ async def test_create_smart_device_with_timeout():
     assert dev.protocol.timeout == 100
 
 
+async def test_create_thin_wrapper():
+    """Make sure thin wrapper is created with the correct device type."""
+    mock = Mock()
+    with patch("kasa.device_factory.connect", return_value=mock) as connect:
+        dev = await SmartDevice.connect(
+            host="test_host",
+            port=1234,
+            timeout=100,
+            credentials=Credentials("username", "password"),
+            device_type=DeviceType.Strip,
+        )
+        assert dev is mock
+
+    connect.assert_called_once_with(
+        host="test_host",
+        port=1234,
+        timeout=100,
+        credentials=Credentials("username", "password"),
+        device_type=DeviceType.Strip,
+    )
+
+
 async def test_modules_not_supported(dev: SmartDevice):
     """Test that unsupported modules do not break the device."""
     for module in dev.modules.values():