Add caddy certificate copier

[SuperQ]

Use a systemd Path unit to copy the SSL certs from Caddy to a well-known location based on the node FQDN. This allows the letsencrypt certs to be re-used by other things (monitoring exporters, non-http services, etc).

• Certs are group readable by ssl-cert.
• Update the Caddy ansible role.

[SuperQ]

Had to rework a few things, tested, now works.