Fixes for test stability (especially microbenchmarks)

Threaded port_server

Slow down timers for ubsan builds

Added unit testing support.

Add lock to shutdown_fd() callback in udp_server.c

Hybrid CQ support

This reverts commit 4f98e25f.

Avoid duplication in Bazel rules by using grpc_cc_libraries rule-creator

Fix semantics of LB policy selection.

Fix HTTP proxy tests

Demote handshake logging msg to DEBUG

Track calls to gpr_now()