Version validation should use the original NuGet.Core regex to ensure compat

[emgarten]

The gallery disallows some versions that are incompatible with NuGet 2.x clients, but misses others. This could be solved by verifying the package version against the original regex used by NuGet.Core.dll.

Regex: https://github.com/NuGet/NuGet2/blob/2.13/src/Core/SemanticVersion.cs#L19

Currently handled by the gallery

• Numeric only release labels, ex: 1.0.0-10 (https://github.com/NuGet/NuGetGallery/blob/master/src/NuGetGallery/Services/PackageService.cs#L565)
• SemVer 2.0.0 multi-labels, ex: 1.0.0-beta.1 (https://github.com/NuGet/NuGetGallery/blob/master/src/NuGetGallery.Core/Packaging/ManifestValidator.cs#L80)

Not handled:

• A label with dash only. ex: 1.0.0-- (not numeric, but also not supported by 2.x)
• Build metadata in the version, ex: 1.0.0+meta
• Invalid versions in dependency ranges. The 2.x client will ignore these internally and turn them into a range accepting all, which can cause problems.

Example packages

https://www.nuget.org/packages/semverA/
https://www.nuget.org/packages/SemVerDashOnly/