Add in security support, make payload protos configurable

Makefile

build.yaml

test/cpp/qps/async_streaming_ping_pong_test.cc

test/cpp/qps/async_unary_ping_pong_test.cc

test/cpp/qps/client.h

test/cpp/qps/qps_driver.cc

test/cpp/qps/qps_openloop_test.cc

test/cpp/qps/qps_test.cc

test/cpp/qps/qps_test_with_poll.cc

test/cpp/qps/server.h

test/cpp/qps/server_async.cc

test/cpp/qps/server_sync.cc

test/cpp/qps/sync_streaming_ping_pong_test.cc

test/cpp/qps/sync_unary_ping_pong_test.cc

test/proto/benchmarks/control.proto

test/proto/benchmarks/payloads.proto

test/proto/benchmarks/stats.proto

tools/run_tests/sources_and_headers.json

vsprojects/vcxproj/qps/qps.vcxproj

vsprojects/vcxproj/qps/qps.vcxproj.filters