Due to changes made in mlua the new scheduler is much simpler. It also
had no real business being part of the device manager, so it has now been
moved to be part of the returned config.
Instead of one function that contains all the device types available in
`automation_devices` a global registry is used were each device can
register itself.
Instead of having to call all the module registration functions in one
place it is possible for each module to register itself in a global registry.
During startup all the all the modules will be registered
automatically.
This does currently have one weakness, to need to ensure that the crate
is linked.
This also results in the conversion being performed when the
ActionCallback is instantiated instead of when it is called, this should
make it easier to catch errors.
