Update NuGet parser to handle dev dependencies

[djpowers]

This adds support for the developmentDependency attribute from packages.config files:

• https://docs.microsoft.com/en-us/nuget/reference/packages-config#examples

It also adds support PackageReferenceelements as used in .csproj files:

• https://docs.microsoft.com/en-us/nuget/consume-packages/package-references-in-project-files#controlling-dependency-assets

(Edit) It also adds developmentDependency support for use in .nuspec files:

• https://docs.microsoft.com/en-us/nuget/reference/nuspec#developmentdependency