Use StrongNameKeyId rather than directly using AssemblyOriginatorKeyFile: fix PublicKeyToken

[dagood]

The projects currently use lines like <AssemblyOriginatorKeyFile>$(KeyFileDir)MSFT.snk</AssemblyOriginatorKeyFile> to set the key to use for strong-name signing. This seems to conflict with the Arcade configuration method, which looks like this:

    <When Condition="'$(StrongNameKeyId)' == 'Microsoft'">
      <PropertyGroup>
        <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)snk/MSFT.snk</AssemblyOriginatorKeyFile>
        <PublicKey>$(MicrosoftPublicKey)</PublicKey>
        <PublicKeyToken>b03f5f7f11d50a3a</PublicKeyToken>
      </PropertyGroup>
    </When>

The result is that the dev branch is building assemblies with the wrong PublicKeyToken. This gets caught when trying to build with bootstrap flow using intermediate nupkgs:

1. On compile phase 1, NuGet.LibraryModel compiles using Microsoft key against prebuilts from NuGet.org that use Shared key in their identities. This means the intermediate nupkg contains a set of DLLs where the identity is Microsoft with references to Shared identities. This already won't work if used: the output doesn't fulfill its own references.

2. On compile phase 2, NuGet.LibraryModel compiles using Microsoft key against source-built DLLs with Microsoft identities and references to Shared identities. Csc fails with CS0012 failing to load:

   Errors
       lib/netstandard2.0/NuGet.Commands.cs(1002,63): error CS0012: The type 'LibraryIdentity' is defined in an assembly that is not referenced. You must add a reference to assembly 'NuGet.LibraryModel, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. [/work/artifacts/source-build/self/src/src/referencePackages/src/nuget.commands/5.1.0/NuGet.Commands.5.1.0.csproj]
       lib/netstandard2.0/NuGet.Commands.cs(1002,63): error CS0012: The type 'NuGetVersion' is defined in an assembly that is not referenced. You must add a reference to assembly 'NuGet.Versioning, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. [/work/artifacts/source-build/self/src/src/referencePackages/src/nuget.commands/5.1.0/NuGet.Commands.5.1.0.csproj]
       lib/netstandard2.0/NuGet.Commands.cs(1002,63): error CS0012: The type 'LibraryDependencyInfo' is defined in an assembly that is not referenced. You must add a reference to assembly 'NuGet.LibraryModel, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. [/work/artifacts/source-build/self/src/src/referencePackages/src/nuget.commands/5.1.0/NuGet.Commands.5.1.0.csproj]
       lib/netstandard2.0/NuGet.Commands.cs(1002,63): error CS0012: The type 'IPackageDownloader' is defined in an assembly that is not referenced. You must add a reference to assembly 'NuGet.Packaging, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. [/work/artifacts/source-build/self/src/src/referencePackages/src/nuget.commands/5.1.0/NuGet.Commands.5.1.0.csproj]
       lib/netstandard2.0/NuGet.Commands.cs(1002,63): error CS0012: The type 'PackageSource' is defined in an assembly that is not referenced. You must add a reference to assembly 'NuGet.Configuration, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. [/work/artifacts/source-build/self/src/src/referencePackages/src/nuget.commands/5.1.0/NuGet.Commands.5.1.0.csproj]
   

I think that I need to rebuild SBRP with this change to generate new intermediate nupkgs that I can use to get further in the sort-of-bootstrapping work I'm doing now.

I've separated this into one commit per global find-replace. (It touches one line in basically every reference package csproj.)

[dagood]

I confirmed this seems to not be a problem in the pre-Arcade code with a spot check of some DLLs from https://dev.azure.com/dnceng/internal/_build/results?buildId=745172&view=results:

// NuGet.Commands, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35
// NuGet.Protocol, Version=5.1.0.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35
// System.Diagnostics.DiagnosticSource, Version=4.0.2.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
// System.IO.Pipes, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
// Microsoft.AspNetCore.Antiforgery, Version=3.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60