This function enumerates all user-accessible UWP packages
and calls the user-provided callback for each package.
This can be used to make GLib aware of the UWP applications
installed in the system.
The function works by using IPackageManager/IPackage UWP interfaces
and XmlLite COM library to parse package manifests.
The function requires COM, and initializes it to a single-thread
appartment model. To ensure this doesn't break anything, either
only use it in a separate thread (COM is initialized on a per-thread
basis), or make sure that the main thread also uses the same COM
model (it's OK to initialize COM multiple times, as long as the same
model is used and as long as init/uninit calls are paired correctly).
