Update installer_base.lib.php as per the discussions / feedback in the thread...

Update installer_base.lib.php as per the discussions / feedback in the thread at https://www.howtoforge.com/community/threads/wip-use-certbot-standalone-to-create-lets-encrypt-ssl-certs-for-ispconfig-servers.80449 by adding check whether the hostname fqdn A record has the same ip with the server before requesting for Let's Encrypt SSL standalone certs.