Support --dev flag

[Greg-Smulko]

• node -v: 16.13.2
• npm -v: 8.1.2
• snyk -v: 1.1022.0
• Command run: snyk monitor ...

Expected behaviour

Dev dependencies should not be reported as a dependency when the --dev flag (see docs) is not passed.

Actual behaviour

The --dev flag is not supported for .NET.

Repro steps

1. Create a project as follows:

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
    </PropertyGroup>
    <ItemGroup>
        <PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="17.3.44" />
    </ItemGroup>
</Project>

2. Build, grab project.assets.json file
3. Run snyk monitor against that file

Please note that the Microsoft.VisualStudio.Threading.Analyzers NuGet package has developmentDependency=true set in their nuspec file (see <developmentDependency>true</developmentDependency> in https://www.fuget.org/packages/Microsoft.VisualStudio.Threading.Analyzers/17.3.44).

Notes

I believe that <developmentDependency>true</developmentDependency> in NuSpec translates to "suppressParent": "All" in project.assets.json file.