Overhaul benchmark control protos and tests themselves

Removed consts to make MSVC happy

Make payloads respect the new defaults

Define resultset.

Added grpc_byte_buffer_reader_readall

Coverage improvements

Enable reasonable default if resp size not specified

Move static value grpc::string_ref::npos definition to cc file

Have not yet added tests with security support, coming soon

Fixing proto dependencies for targets that aren't libraries.

Mirrors a node test, and fix a bug that it found

Mark a method with GRPC_OVERRIDE to avoid compiler warning

Needed to properly implement pollset reset

Create a separate utility for reporting.

Add simple profiling instrumentation for C#

If we already have a status from the wire when we're disconnecting,
leave it in place - don't overwrite it. Fixes disappearing_server_test.

Remove some unused options and make server_threads relevant
Start stubbing out better qps/core calculations