Merge pull request #9665 from jtattermusch/cmake_csharp_extension

src/csharp/Grpc.Core.Tests/project.json

src/csharp/Grpc.Core/NativeDeps.Windows.targets

src/csharp/Grpc.Examples.MathClient/project.json

src/csharp/Grpc.Examples.MathServer/project.json

src/csharp/Grpc.Examples.Tests/project.json

src/csharp/Grpc.HealthCheck.Tests/project.json

src/csharp/Grpc.IntegrationTesting.Client/project.json

src/csharp/Grpc.IntegrationTesting.QpsWorker/project.json

src/csharp/Grpc.IntegrationTesting.Server/project.json

src/csharp/Grpc.IntegrationTesting.StressClient/project.json

src/csharp/Grpc.IntegrationTesting/project.json

src/csharp/Grpc.Reflection.Tests/project.json

src/csharp/README.md

src/csharp/buildall.bat

templates/src/csharp/build_options.include

tools/run_tests/artifacts/artifact_targets.py

tools/run_tests/artifacts/build_artifact_csharp.bat

tools/run_tests/helper_scripts/pre_build_csharp.bat

tools/run_tests/run_tests.py