Picked this up while updating the [Fan platform
PR](https://github.com/home-assistant/core/pull/116605) for HA. The
smart fan module was not correctly deriving from the common interface
and the speed_level is reported as >0 when off.
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.
Enables the Fan interface for devices supporting that component.
Currently the only device with a fan is the ks240 which implements it as
a child device. This PR adds a method `get_module` to search the child
device for modules if it is a WallSwitch device type.
In order to support the ks240 which has children for the fan and light
components, this PR adds those modules at the parent level and hides the
children so it looks like a single device to consumers. It also decides
which modules not to take from the child because the child does not
support them even though it say it does. It does this for now via a
fixed list, e.g. `Time`, `Firmware` etc.
Also adds fixtures from two versions and corresponding tests.
