[PATCH v14 0/8] MR6766: dlls/wintypes: Implement Windows.Foundation.Collections.PropertySet.

[Vibhav Pant (＠vibhavp)]

The implementation is backed by a smaller `IWinePropertySetImpl` interface for core operations (insertion, lookup, removal, iteration), which currently uses an `rb_tree` to store `HSTRING`-`IInspectable *` value pairs.

If needed, the `IWinePropertySetImpl` implementation can be later swapped out with a hash table for performance reasons, as `PropertySet` does not have an enumeration order guarantee, at least according to the MSDN docs.

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  v14:  
https://gitlab.winehq.org/wine/wine/-/merge_requests/6766