Remove gcloud auth activate-service-account from Kokoro Mac build

Add OAuth2 protocol in GRPCClient

Add Kokoro tests to build gRPC with an updated submodule

Prevent fd_orphan from calling shutdown(fd) when release_fd is true

Add support for service configs to c-ares resolver.

Test grpc++_unsecure in Bazel build

Make port picking functions overridable

Set up Mac interop test to work in Kokoro env

Delete unused macos grpc_basictests.cfg

Condition variables are not latches

Revert "Reintroduce a lambda capture as part of C++11-izing code"

Remove unused stress test script

Improve flakes query

QPS Driver Tweaks

Fix another two memory leak points in Cronet transport

Fix warning in GRPCCall.h

Add a default delete override for the interface

Add bazel tests to Kokoro

Split up macos basictests into dbg and opt and set num of jobs to 1.

Prepopulate more pip packages on kokoro linux

Make tsi handshaker result unused bytes const

Node: document that root_certs in createSsl is optional

It appears that omitting it causes grpc to use the hosts' default cert data.
This was brought up (as I had implemented this method incorrectly) in:
https://github.com/mixer/etcd3/issues/28#issuecomment-319510441