Praefect allowed to use TLS address to listen on in
combination with certificate and its key to be used for it.
'metadata' package refactored, so TLS address can be passed
into the Gitaly.
Documentation fixed and example file filled with proper vals.
Closes: https://gitlab.com/gitlab-org/gitaly/-/issues/1698
When investigating the integration of praefect in the GDK and Omnibus it
seemed that using sockets is much more convenient. From a configuration
perspective the behaviour of Gitaly is largely copied.
Closes: https://gitlab.com/gitlab-org/gitaly/issues/1523