[8.x] Retry connection if DNS resolution fails

[deleugpn]

Recently I've been investigating some connection failures:

SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known (SQL: select * from ...)

Upon investigation, I noticed that this happened about 36 times out of 130,396 requests in. Although extremely low (0.02%), it is still quite disruptive to have some requests throwing 500 Internal Server Error and writing database connection logs.
AWS Support has informed that due to transient network issues, it is possible that an extremely small number of connections to RDS or Elasticache might fail and that their engineers are always working on trying to reduce even further these errors. Since it's a rare event of connectivity issues, retrying the connection seem to be a viable option and doing this on my own project seems to be so much harder than using Laravel's built-in system for reconnection.

[GrahamCampbell]

This should target the 6.x branch. :)

[driesvints]

Yep, indeed. @deleugpn can you send this to 6.x?