Manual upmerge from v1.0.x

port_posix: use IPv4+IPv6 sockets to check for a free port.

Clang-format code

Fix docker go

UserResource does not reference tcp endpoint on windows

remove concurrent ruby dep from gemspec template

Bypass poll thread if wakeup fd is set

Pretty print outgoing headers

This allows the port picker to function across dual-stack and
IPv4/IPv6-only environments.

For a port to be considered available, the kernel must support at least
one of (IPv6, IPv4), and the port must be available on each supported
family.

Also use the bool type where feasible.

This is based on http://cl/97155408 (for those who can read it.)

Check on *target, not target

Fixed leak upon duped serverlist updates

Add new flags to Python stress client

Add use_tls, use_test_ca, and server_host_override flags to Python
stress client. These are needed to run the stress client against a local
server that is using tls.

C#: Update System.Interactive.Async to 3.1.1

tcp_client_posix: Don't overwrite error descr.

Reduce noise in interop test output

Expose message limit constants so that users can reference them

Rewrote connectivity status logic for gRPC LB

Fix windows benchmarks and upload all 3 reports