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_discovery.py

@@ -1,4 +1,6 @@
 # type: ignore
+# ruff: noqa: S106
+
 import asyncio
 import re
 import socket
@@ -16,8 +18,8 @@ from kasa import (
     KasaException,
 )
 from kasa.deviceconfig import (
-    ConnectionType,
     DeviceConfig,
+    DeviceConnectionParameters,
 )
 from kasa.discover import DiscoveryResult, _DiscoverProtocol, json_dumps
 from kasa.exceptions import AuthenticationError, UnsupportedDeviceError
@@ -128,7 +130,7 @@ async def test_discover_single(discovery_mock, custom_port, mocker):
     if discovery_mock.default_port == 80:
         assert x.alias is None
 
-    ct = ConnectionType.from_values(
+    ct = DeviceConnectionParameters.from_values(
         discovery_mock.device_type,
         discovery_mock.encrypt_type,
         discovery_mock.login_version,
@@ -164,6 +166,60 @@ async def test_discover_single_hostname(discovery_mock, mocker):
         x = await Discover.discover_single(host, credentials=Credentials())
 
 
+async def test_discover_credentials(mocker):
+    """Make sure that discover gives credentials precedence over un and pw."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.discover._DiscoverProtocol.wait_for_discovery_to_complete")
+
+    def mock_discover(self, *_, **__):
+        self.discovered_devices = {host: MagicMock()}
+
+    mocker.patch.object(_DiscoverProtocol, "do_discover", mock_discover)
+    dp = mocker.spy(_DiscoverProtocol, "__init__")
+
+    # Only credentials passed
+    await Discover.discover(credentials=Credentials(), timeout=0)
+    assert dp.mock_calls[0].kwargs["credentials"] == Credentials()
+    # Credentials and un/pw passed
+    await Discover.discover(
+        credentials=Credentials(), username="Foo", password="Bar", timeout=0
+    )
+    assert dp.mock_calls[1].kwargs["credentials"] == Credentials()
+    # Only un/pw passed
+    await Discover.discover(username="Foo", password="Bar", timeout=0)
+    assert dp.mock_calls[2].kwargs["credentials"] == Credentials("Foo", "Bar")
+    # Only un passed, credentials should be None
+    await Discover.discover(username="Foo", timeout=0)
+    assert dp.mock_calls[3].kwargs["credentials"] is None
+
+
+async def test_discover_single_credentials(mocker):
+    """Make sure that discover_single gives credentials precedence over un and pw."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.discover._DiscoverProtocol.wait_for_discovery_to_complete")
+
+    def mock_discover(self, *_, **__):
+        self.discovered_devices = {host: MagicMock()}
+
+    mocker.patch.object(_DiscoverProtocol, "do_discover", mock_discover)
+    dp = mocker.spy(_DiscoverProtocol, "__init__")
+
+    # Only credentials passed
+    await Discover.discover_single(host, credentials=Credentials(), timeout=0)
+    assert dp.mock_calls[0].kwargs["credentials"] == Credentials()
+    # Credentials and un/pw passed
+    await Discover.discover_single(
+        host, credentials=Credentials(), username="Foo", password="Bar", timeout=0
+    )
+    assert dp.mock_calls[1].kwargs["credentials"] == Credentials()
+    # Only un/pw passed
+    await Discover.discover_single(host, username="Foo", password="Bar", timeout=0)
+    assert dp.mock_calls[2].kwargs["credentials"] == Credentials("Foo", "Bar")
+    # Only un passed, credentials should be None
+    await Discover.discover_single(host, username="Foo", timeout=0)
+    assert dp.mock_calls[3].kwargs["credentials"] is None
+
+
 async def test_discover_single_unsupported(unsupported_device_info, mocker):
     """Make sure that discover_single handles unsupported devices correctly."""
     host = "127.0.0.1"