Implement Subdomains so they can be used in handles

Subdomain:

[x] Maybe add subdomains 🔗https://caddyserver.com/docs/caddyfile/patterns#wildcard-certificates
[x] Builds on https://github.com/Monviech/os-caddy-plugin/issues/26 , so it might get complicated in the template.

# Reverse proxy entry "example.com HTTP Reverse Proxy":
*.example.com:443 {
    tls {
        dns cloudflare 1484053787dJQB8vP1q0yc5ZEBnH6JGS4d3mBmvIeMrnnxFi3WtJdF
    }

    # subdomain for autodiscover.example.com
    @autodiscover.example.com host autodiscover.example.com:443
    handle @autodiscover.example.com {
        reverse_proxy 192.168.1.1:443
    }

    # Local handle for any other domains in that subdomain
    handle {
        reverse_proxy 172.16.1.1:4444
    }
}

Monviech / os-caddy-plugin

Implement Subdomains so they can be used in handles #31