Copy dSYMs from xcframeworks next to the app's dSYM

[rolfbjarne]

Copy dSYMs from xcframeworks next to the app's dSYM, so that they're added to the archive when the app is archived.

A workaround is to add this to the app's csproj:

<Target Name="CopydSYMsFromXCFrameworks" AfterTargets="_GenerateDSym">
    <ItemGroup>
        <dSYMsForXCFrameworks Include="@(_FrameworkNativeReference->'%(RootDir)%(Directory)/../dSYMs/%(Filename).framework.dSYM')" />
    </ItemGroup>
    <Copy SourceFolders="@(dSYMsForXCFrameworks)" DestinationFolder="$(AppBundleDir)/../" />
</Target>

See also #17318 and #14598.