Parse .NET Core project.json version strings as VersionRange

[joelverhagen]

Fix NuGet/Home#3070 and NuGet/Home#3095.

In a project.json you can specify a dependency with a version range, e.g. a floating version like 1.0.0-*. The problem was that we were simply parsing this string as a NuGetVersion (which is a specific version) not a VersionRange. This problem is only occurring in .NET Core project.json projects, not UWP project.json.

Right now, our UI has a limitation where it only shows a specific version (not a version range). For this reason, we will now parse this string as a version range but only display the minimum of the version range. This is not an ideal solution since it's ugly and unhelpful but we are already doing this today with UWP project.json projects. The improvement to the UI to display version ranges is tracked here: NuGet/Home#3101.

/cc @alpaix @yishaigalatzer @rohit21agrawal @mlorbetske

[joelverhagen]

/cc @emgarten

[emgarten]

This looks much better, but note that the min version could be null here. I'm not sure how the .NET core project system handles that. Ex: "nuget.versioning": "( , 3.0.0]" is valid in project.json.

[joelverhagen]

Yes, this is a good point. However, this is already an issue in UWP project.json projects (tracked here:
NuGet/Home#3109). This PR simply makes .NET Core projects more consistent with UWP project.json.

Do you think it's reasonable address the minimum version problem as a separate PR?

[emgarten]

Do you think it's reasonable address the minimum version problem as a separate PR?

yes

🚀