Improved C# grpc server implementation to be able to register call handlers

Move pollset_kick wfd creation/destruction out of freelist lock

This was an observed source of contention at higher thread counts where
we could overrun the freelist cap.

Adding support for loading the SSL roots from an environment variable.

Added usage info to csharp/README.md

Fix some memory leaks

Docker

Prevents a use-after-free

Prototype of gRPC C# library (Core and API examples)

Added a lot more information to Node README

Eliminate condvar in chttp2 transport

Fix contention in alarm lists

There's no need for this branch at all.

Theres no need for every thread to exit polling early if an alarm might finish, so there's no need to contend here.

Added missing pingpong tests to cloud prod test
Cleaned up test output and inserted them into a google.visualization.Datatable object

Fix up feature test macros

Add a tsan suppression file with OPENSSL_cleanse and use it in run_tests

Let the http2 transport issue a read request before pumping bytes into it.

Back-end for new core API