After `DeviceWatcher::Start()` gets called, `DeviceWatcher` enumerates through a list of all `DeviceInformation` objects on the current system through the `Added` event handlers, dispatching `EnumerationCompleted` once this has finished. This MR implements this functionality. -- v2: windows.devices.enumeration: Implement initial device enumeration for DeviceWatcher::Start(). windows.devices.enumeration: Implement EnumerationCompleted handler for DeviceWatcher. windows.devices.enumeration: Implement CreateWatcher. windows.devices.enumeration: Implement Added handler for DeviceWatcher. windows.devices.enumeration: Add tests for initial device enumeration in DeviceWatcher. https://gitlab.winehq.org/wine/wine/-/merge_requests/7997