fix: close sockets on connection initialize timeout

[rpeng]

When timeouts are set on the client, there is potential for a resource leak when timeouts occur during connection initialization.

When timeout errors are thrown during connection initialization, the connection object itself is not created (nil) and the client won't be able to properly close the connection.

This causes the created socket to stay in either an ESTABLISHED or CLOSE_WAIT state, while the client no longer has a reference to it, effectively causing a leak.

Steps to repro:

In the client:

# irb or rails c
client = HTTP.timeout(5)

client.get("https://www.example.org").body.to_s # or use 240.0.0.0
client.get("https://www.example.org").body.to_s
client.get("https://www.example.org").body.to_s

Simultaneously:

1. Set up a mitm to intercept example.org, and add network conditioning to make the request very slow. Or you can use a black hole IP such as 240.0.0.0
2. Check the sockets opened by the ruby process:

watch -n 1 "lsof -i -P | grep PROCESS_PID" # replace PROCESS_PID with the rails process pid

You'll notice that sockets will stay in ESTABLISHED or CLOSE_WAIT as you make more and more requests that time out.

ruby    28497 rpeng   21u  IPv4 43444771      0t0  TCP f6eb5410737c:57558->93.184.216.34:443 (CLOSE_WAIT)
ruby    28497 rpeng   23u  IPv4 43449275      0t0  TCP f6eb5410737c:56876->93.184.216.34:443 (CLOSE_WAIT)
ruby    28497 rpeng   24u  IPv4 43452649      0t0  TCP f6eb5410737c:34242->93.184.216.34:443 (ESTABLISHED)
ruby    28497 rpeng   25u  IPv4 43458906      0t0  TCP f6eb5410737c:55366->93.184.216.34:443 (ESTABLISHED)
ruby    28497 rpeng   26u  IPv4 43461133      0t0  TCP f6eb5410737c:37510->93.184.216.34:443 (ESTABLISHED)

The fix ensures that a socket is closed if any timeouts happen during initialization, though I suspect we could make this even more stringent (e.g. on any StandardError, we ensure that we send @socket.close if a socket exists and is open)

[rpeng]

Forwardable and def_delegators don't really work with safe nav operators

[ixti]

LGTM