Do not output ref assemblies

[espenrl]

There is a issue with NuGet packages which contains ref assemblies like Microsoft.CSharp and System.Runtime.Serialization.Primitives. Ref assemblies are only for compilation, and not for runtime execution. I've learned a lot about .NET Standard, NuGet and MSBuild during the last hours. :)

ResolvedCompileFileDefinitions points to these ref files, and my fix is as simple as replacing \ref\ with \lib\. Ref and lib should always come in pair, so it should be an okay solution to the problem.

I do not know if MSBuild ever will produce forward slashes. The code only handles backward slashes.

Fixes H.NSwag.Generator

I'm using H.NSwag.Generator which is a great tool. I can only build using full MSBuild. It fails using dotnet build because Microsoft.CSharp.dll can't be loaded. I've tested and verified that H.NSwag.Generator works using this fix for dotnet build.

[HavenDV]

Hello. Thanks a lot for this PR, I didn't know about ref directories in nuget package
Can you quickly test if this will work?
@(ResolvedCompileFileDefinitionsWithoutSystem->Replace('\ref\', '\lib\')->Replace('/ref/', '/lib/'))

[espenrl]

It works. I've added the change.

without fix

Added generation time reference: <redacted>\.nuget\packages\microsoft.csharp\4.7.0\ref\netstandard2.0\Microsoft.CSharp.dll

with fix

Added generation time reference: <redacted>\.nuget\packages\microsoft.csharp\4.7.0\lib\netstandard2.0\Microsoft.CSharp.dll

[espenrl]

Oh, btw. It's a bit confusing that the latest packages for H.NSwag.Generator are in the 13.15.x range, while the highest version is in the 13.16.x range. Dependabot always suggest me to update, and I never really know if there is a new 13.15.x release. It would have been awesome if this was sorted out.

[HavenDV]

It happened due to the fact that the latest version of NSwag had problems that were not solved for a long time:
RicoSuter/NSwag#4012
RicoSuter/NJsonSchema#1522
I think this issue is already settled, at least 4 months to accept the PR, and I will release a new version already according to the latest version of NSwag after accepting this PR.

[espenrl]

I see, you're following the versioning of NSwag. Makes sense.