httpcaddyfile: Fix bind when IPv6 is specified with network (#4950)
httpcaddyfile: Fix bind when IPv6 is specified with network (#4950)

* fix listening on IPv6 addresses: use net.JoinHostPort

Commit 1e18afb5c862d62be130d563785de5c58f08ae8e broke my caddy setup.
This commit fixes it.

* Refactor solution; simplify, add descriptive comment

* Move network to host, not copy

Co-authored-by: Matthew Holt <6e15340bc34d98c823445cca0475cc9127379d4b@users.noreply.github.com>
l3dlp/caddy,l3dlp/caddy,l3dlp/caddy