Refactoring within Python RPC Framework

Add missing GRPC_OVERRIDE, NFC

Testing asan configuration with the latest clang compiler fails due to
the warning `-Winconsistent-missing-override`. This patch fixes it.

strcmp: change all !str[n]cmp to str[n]cmp == 0

Change all !str[n]cmp to be str[n]cmp == 0 consistently across the codebase.

Issue #231

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

The assembly and face layers were mostly redundant except that the
assembly layer had far-better interfaces and the face layer had more
of a reason to exist. Now they are merged.

C++ Credentials Rework

Secure python interop (plus Python<->Python interop unit tests)

Also refactor the interop package to perform client-server interop
testing in a unit test.

This optional value should only be passed in tests.

Don't merge OpenSSL into C++ upper layer libraries; only C.

Reintroduce sleep on backup thread

Removes unused dependencies

Grpc ruby cleanup client stub initialize fix hostname bug

C# refactoring and code cleanup

Fix Python protoc plugin test workflow

Crash in channel/server creation if grpc_init not called

Moves the Python protoc plugin output directory to an auto-generated
temporary directory. Has the build configuration set by environment
variable (consistent with `tools/run-tests/run_tests.py`'s set envvars).

Don't call grpc_create_chttp2_transport after destroying the server

Grpc ruby update server api

Add synchronization in server_secure_chttp2.c to avoid propagating a
completed handshake past that layer to a potentially already destroyed
server.