feat: add support for tcp sockets for php-fpm

[sjinks]

Because we have plans to add the Cron Control Runner into Dev Env (Automattic/vip-container-images#783), it would be nice if the runner could connect to a tcp socket (nginx needs tcp to connect to a different container, and php-fpm does not support multiple listeners for the same process pool).

This PR adds support for tcp:, tcp4:, and tcp6: sockets.

It was tested in the dev env:

root@ccab9ede2bf0:/app# /usr/bin/cron-control-runner -fpm-url tcp://127.0.0.1:9000 -wp-cli-path /usr/local/bin/wp -wp-path /wp -prom-metrics-address :4444 -debug
2024/06/20 03:48:56 Initializing metrics
2024/06/20 03:48:56 INFO: Using FPM runtime at "tcp://127.0.0.1:9000"
2024/06/20 03:48:56 INFO: cron runner has started all processes, running with debug mode set to true
2024/06/20 03:48:56 Listening for metrics on ":4444"
2024/06/20 03:48:56 DEBUG: starting thread "http://vip-local.vipdev.lndo.site"
2024/06/20 03:48:56 INFO: starting watcher for site {URL:http://vip-local.vipdev.lndo.site}, initial delay: 5.754629049s
2024/06/20 03:49:02 DEBUG: initial delay has elapsed for {URL:http://vip-local.vipdev.lndo.site}, starting to run events
2024/06/20 03:49:02 DEBUG: getEvents: got 0 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:49:30 DEBUG: getEvents: got 1 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:49:31 DEBUG: runEvents: worker-8 finished job event(url="http://vip-local.vipdev.lndo.site", ts=1718855359, action="7715f1b533e885efdb5e3ef10d2ba3e8", instance="40cd750bba9870f18aada2478b24840a") after 46.282562ms
2024/06/20 03:50:02 DEBUG: getEvents: got 0 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:50:32 DEBUG: getEvents: got 0 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:51:04 DEBUG: getEvents: got 0 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:51:35 DEBUG: getEvents: got 3 events for site http://vip-local.vipdev.lndo.site
2024/06/20 03:51:35 DEBUG: runEvents: worker-7 finished job event(url="http://vip-local.vipdev.lndo.site", ts=1718855479, action="7715f1b533e885efdb5e3ef10d2ba3e8", instance="40cd750bba9870f18aada2478b24840a") after 36.105326ms
2024/06/20 03:51:35 DEBUG: runEvents: worker-6 finished job event(url="http://vip-local.vipdev.lndo.site", ts=1718855479, action="29ef625a054a0b386093ac9c46a2c616", instance="40cd750bba9870f18aada2478b24840a") after 42.646596ms
2024/06/20 03:51:35 DEBUG: runEvents: worker-5 finished job event(url="http://vip-local.vipdev.lndo.site", ts=1718855479, action="3ff9331542b8cdbaae37688e538b5104", instance="40cd750bba9870f18aada2478b24840a") after 46.852341ms