Extendded from Osixia/phpldapadmin

• Adds ca-certificates package
• Points ldap.conf TLS_CACERT to the ISRG Root X1 CA (allows using let's Encrypt certificates for ldaps)
• Rips out the config.php bootstrap from startup
• Expects an existing config (ie a volume mounted configMap) present at /container/service/phpldapadmin/assets/config/config.php
• The read-only config mount will be copied to /var/www/phpldapadmin/config/config.php at startup and chowned to www-data