NuGet API v3

[JoC0de]

This PR adds support for NuGet repositories that are using the API version 3. This involves some big changes. e.g.:

• Added INugetPackage interface with 3 different implementations for v2, v3 or local NuGet package sources.
• Version Numbers are now normalized according the Microsoft documentation

[igor84]

Nice work on this big feature. Can't wait to try it out :)

[JoC0de]

@popara96 @igor84
I changed the way NugetPackageVersion.cs normalizes versions because version number comparison didn't comply to the Microsoft documentation.
In the implementation before the version 4.39.6.0 was not treated equal to 4.39.6 when calling Equals or GetHashCode, only Compare had the correct behavior. To achieve this I changed NugetPackageVersion.NormalizedVersion to not contain the additional 0 at the end. So Equals can just use the NormalizedVersion.
As INugetPackage.Version returns the NormalizedVersion this has the side effect that e.g. the name of the output folder where the Package content is stored changes. Do you think this is a problem?
I am not sure if Microsoft already removes the .0 in the API response but at least in the UI they removed it e.g. https://www.nuget.org/packages/StyleCop.MSBuild/4.7.49#versions-body-tab has no .0.

[igor84]

I never encountered a version like that (that I am aware of) so I don't see any issue with this change.

[igor84]

I just noticed that this returns null but on line 40 we are passing NugetPackageV2 to FillFromNuspec method that has this line: package.Versions.Add(package.PackageVersion); which will cause NullReferenceException, right? Should we just change that line to package.Versions?.Add(package.PackageVersion);

[JoC0de]

you are right. It will be fixed in #568