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/module.py

@@ -4,7 +4,10 @@ from __future__ import annotations
 
 import logging
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING
+from typing import (
+    TYPE_CHECKING,
+    TypeVar,
+)
 
 from .exceptions import KasaException
 from .feature import Feature
@@ -14,6 +17,8 @@ if TYPE_CHECKING:
 
 _LOGGER = logging.getLogger(__name__)
 
+ModuleT = TypeVar("ModuleT", bound="Module")
+
 
 class Module(ABC):
     """Base class implemention for all modules.