NuGet Pack with assembly references support

[WebDucer]

What You Are Seeing?

With current NuGetPackSettings it is not possible to add assembly references to the NuGet package.

What is Expected?

Possibility to add assembly references to NuGet package (like with NuSpecDependency for NuGet dependencies of the package).

What version of Cake are you using?

• 0.32.1

Are you running on a 32 or 64 bit system?

• x64

What environment are you running on? Windows? Linux? Mac?

• Win 10
• macOS

Are you running on a CI Server? If so, which one?

• GitLab CI

XML example

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://schemas.microsoft.com/packaging/2012/06/nuspec.xsd">
  <metadata>
    <id>RSAG.Xam.RtfEditor</id>
    <version>0.1.0-alpha0005</version>
    <title>RTF edit and view controls</title>
...
    <dependencies>
      <group targetFramework=".NETStandard2.0">
        <dependency id="Syncfusion.Xamarin.DocIO" version="16.4.0.54" />
        <dependency id="Xamarin.Forms" version="3.4.0.1029999" />
      </group>
      <group targetFramework="MonoAndroid5.0">
        <dependency id="Syncfusion.Xamarin.DocIO" version="16.4.0.54" />
        <dependency id="Xamarin.Forms" version="3.4.0.1029999" />
      </group>
      <group targetFramework="Xamarin.iOS1.0">
        <dependency id="Syncfusion.Xamarin.DocIO" version="16.4.0.54" />
        <dependency id="Xamarin.Forms" version="3.4.0.1029999" />
      </group>
      <group targetFramework="UAP0.0">
        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.7" />
        <dependency id="Syncfusion.Xamarin.DocIO" version="16.4.0.54" />
        <dependency id="Xamarin.Forms" version="3.4.0.1029999" />
      </group>
    </dependencies>
    <frameworkAssemblies>
      <frameworkAssembly assemblyName="Mono.Android.Export" targetFramework="MonoAndroid1.0" />
    </frameworkAssemblies>
  </metadata>
</package>

[daveMueller]

Here is a pull request for this #2516 . Would be cool if somebody will review.