Add custom dialer to tableflip for listening on 0.0.0.0
Problem to solve
When configuring Praefect and Gitaly, it is much more convenient to listen on
0.0.0.0 rather than on the internal IP address so that the same configuration can easily be rolled out to many nodes in a fleet.
However, tableflip isn't happy about this which means the admin also needs to run
gitlab-ctl restart [gitaly|praefect]
Add a custom dialer.
See discussion https://github.com/cloudflare/tableflip/pull/45