www/caddy: Add reloadssl rc(8) command

service caddy reloadssl instructs Caddy to reload its TLS
certificates. This is useful when using Caddy with ACME DNS
providers, as it allows for the renewal of certificates without
manually deleting the old ones and restarting Caddy.

PR: 274085
(cherry picked from commit 528ac9e77df40d5e8bf424b8a1255be4d2986ec9)