Update installer_base.lib.php accordingly to [Jesse Norell's suggestion](https://www.howtoforge.com/community/threads/wip-use-certbot-standalone-to-create-lets-encrypt-ssl-certs-for-ispconfig-servers.80449/#post-381238) which is supposedly more prudent.

Update installer_base.lib.php to change if (!@is_dir($le_live_dir) && ($svr_ip != $dns_ip)) to else.

Update installer_base.lib.php to use php instead of cli / shell command in renaming files and creating symlinks.

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.

Update installer_base.lib.php to fix lines 2439-2441; remove line with .csr; use $conf['hostname'] if not localhost or empty.

Update installer_base.lib.php to use certbot standalone to create SSL certs for ISPConfig server(s).

Patch 4

See merge request ispconfig/ispconfig3!833

Patch 3

See merge request ispconfig/ispconfig3!832

Patch 2

See merge request ispconfig/ispconfig3!831

Patch 1

See merge request ispconfig/ispconfig3!830

Add ci test for php syntax

See merge request ispconfig/ispconfig3!827

# Conflicts:
#   .gitlab-ci.yml