* Save all the NativeReference metadata in binding resource packages.
* Copy all the NativeReference metadata to new items when resolving native references.
This makes it possible to set custom metadata on NativeReferences, and have that
metadata show up when it's needed, which might not be in the same project (for instance
if the native reference is in a binding project, we might want the custom metadata
when we load the native references from the binding project's resource package -
another case is when app extensions have native references, we might want any custom
metadata in the main executable project to know how to handle certain types of native
references).
Also sort the metadata we write to binding resource packages, so that the output
is stable. This required updating the corresponding tests.
Augment the CreateBindingResourcePackage to support creating a zipped binding
resource package (which is just a zipped version of the binding resource
package). This can either be manually chosen by the new 'Compressed' property,
or automatically detected (create a zipped version when there's a symlink in
the binding resource package).
The default is to not create a zipped version in legacy Xamarin, and
automatically detect for .NET.
The problem this is trying to solve is when creating a NuGet package - NuGet
doesn't handle symlinks correctly and it's not possible to create a NuGet with
symlinks. Instead we need to create a zipfile with all the binding resources.
The default has been chosen so that we automatically create a zip file when
it's required for .NET, while still maintaining old behavior with legacy
Xamarin.
Rolf Bjarne Kvinge