Remove dead code from WCF repository & simplify msbuild logic

[ViktorHofer]

The motivation for this change is that we in runtime owned most of the dead code in this repository and I just stumbled over it while looking into this repository. I tested the changes by diffing the assembly metadata.

Two commits:

1. Remove dead code from WCF repository

• .gitmirrorall, DotnetCLIVersion.txt, ., harvest.targets,
  Configurations.props, archgroups.props, configurationgroups.props,
  DefaultGenApiDocIds.txt, LicenseHeader.txt, osgroups.props,
  properties.props, TargetFramework.props, Configurations.props and
  targetgroups.props were all used by dotnet/buildtools tooling that
  has been removed more than five years ago from this repository.
• uwp.targets, Publishing.props aren't used anymore (Publishing.props
  isn't necessary anymore as Arcade defaults to version 3).
• build.ps1/build.sh code was copied from runtime and doesn't apply to
  this repository.
• project files: IsBuilding, IsHarvesting are dead properties.
  PackageReference to Microsoft.NETFramework.ReferenceAssemblies is
  added automatically by the SDK. Use EnableDefaultItems=false instead
  of removing Compile items and resources. Remove outdated comment.

2. Simplify msbuild logic

• Remove dead properties from TestProperties.props and move the
  remaining ones directly into Directory.Build.props
• Fix dotnet-svcutil-lib.csproj condition which was conditioning on the
  ConfigurationGroup property which wasn't set anymore.
• Remove dead properties (which now are either the default or were
  removed) from Versions.props. Move one version property from
  Directory.Build.props into Versions.props
• Remove the unnecessary "ToolsVersion="14.0" xmlns="..."" tag.
  MSBuild/VS doesn't require that anymore.
• Drastically simplify logic in Versions.props (sync with what we have
  in runtime) by removing the now unnecessary targets. Move what
  remains directly into Directory.Build.*.
• Remove dead code from ReferenceAssemblies.props and move the
  remainder into Directory.Build.props.

[mconnew]

Indentation is wrong on this line. First character is a tab, then there's spaces.

[ViktorHofer]

Fixed via 646c506

[mconnew]

Just the one indentation that needs fixing, then it's good. It's possible we might have problems with the release CI, that's impossible to validate before hand. We'll ping you if that's the case.