Final 5.1.0 insertion and shipping

[rrelyea]

5.1.0.6013 Build
ReleaseId via AzDO: 322942

• Shepherd insertions into VS-16.1.0-preview4-- inserted via the setup/msbuild/nuget joint insertion

• Shepherd insertions into SDK
  Insert NuGet Build 5.1.0-rtm.6013 into sdk dotnet/sdk#3217 -- sdk release/2.2.3xx branch
  Insert NuGet Build 5.1.0-rtm.6013 into sdk dotnet/sdk#3218 -- sdk release/2.1.7xx branch

• Shepherd insertions into CLI
  Insert NuGet Build 5.1.0-rtm.6013 into cli dotnet/cli#11303 -- cli release/2.2.3xx branch
  Insert NuGet Build 5.1.0-rtm.6013 into cli dotnet/cli#11304 -- cli release/2.1.7xx branch

• Review and polish release notes

• Send PR with release notes to team - first draft 5.1 release notes docs.microsoft.com-nuget#1442

• publish release notes - @karann-msft

• draft team tweet, etc... - @karann-msft

• Ship packages- @rrelyea

• Ship nuget.exe - @loic-sharma & @rrelyea - NuGet.Services.Index/pull/143

Wait a few weeks

• Bless nuget.exe if feedback after a few weeks is good.

[nkolev92]

@heng-liu blessed nuget.exe when we shipped 5.2