Merge pull request #7660 from jtattermusch/google_apis_auth_coreclr

src/csharp/Grpc.Auth/Grpc.Auth.csproj

src/csharp/Grpc.Auth/Grpc.Auth.nuspec

src/csharp/Grpc.Auth/packages.config

src/csharp/Grpc.Auth/project.json

...ationTesting.Client/Grpc.IntegrationTesting.Client.csproj

src/csharp/Grpc.IntegrationTesting.Client/packages.config

...esting.QpsWorker/Grpc.IntegrationTesting.QpsWorker.csproj

src/csharp/Grpc.IntegrationTesting.QpsWorker/app.config

...ationTesting.Server/Grpc.IntegrationTesting.Server.csproj

src/csharp/Grpc.IntegrationTesting.Server/packages.config

...rp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj

src/csharp/Grpc.IntegrationTesting/InteropClient.cs

src/csharp/Grpc.IntegrationTesting/packages.config

templates/src/csharp/Grpc.Auth/project.json.template

test/distrib/csharp/DistribTest/App.config

test/distrib/csharp/DistribTest/DistribTest.csproj

test/distrib/csharp/DistribTest/packages.config