PHP 8 strict fixes, #6419

Closes #6419

See merge request ispconfig/ispconfig3!1670

Fixed typo. Wrong "subjectAltName" with leading dot when using self-signed certificates.

See merge request ispconfig/ispconfig3!1671

APS deletion follows symlink

See merge request ispconfig/ispconfig3!1666

Resolve "Change default URL of phpmyadmin and webmail to apps vhost"

Closes #6415

See merge request ispconfig/ispconfig3!1665

add mail_relay_domain API functions #6399

See merge request ispconfig/ispconfig3!1644

Fix var name issue crippling vhost_rewrite_v6?

Closes #6414

See merge request ispconfig/ispconfig3!1663

closes #6414

Update .gitlab-ci.yml file to account for beta releases

See merge request ispconfig/ispconfig3!1662

De lang updates

See merge request ispconfig/ispconfig3!1660

Merge branch '6411-add-ubuntu-22-04-specific-config-settings-and-version-detection-code' into 'develop'

Resolve "Add Ubuntu 22.04 specific config settings and version detection code"

Closes #6411

See merge request ispconfig/ispconfig3!1661

Resolve "Use predefined DH params file to speed-up installation"

Closes #6390

See merge request ispconfig/ispconfig3!1659

Use central predefined 4096 bit DH params file (from Mozilla https://ssl-config.mozilla.org/ffdhe4096.txt ) instead of creation one via openssl command to speed up the installation. Thank you to @ahrasis for code suggestions.

Merge branch '6393-websites-php-version-gets-accidentally-altered-by-admin-if-websites-php-version-is-client_id-0' into 'develop'

Resolve "Websites php version gets (accidentally) altered by admin if websites php version is client_id != 0"

Closes #6393

See merge request ispconfig/ispconfig3!1657

Fix issue that PHP version of a site gets altered when an admin edits the site when domain limit mode is active.

Resolve "Add support for RHEL 9 and compatible clones"

Closes #6373

See merge request ispconfig/ispconfig3!1656

Match conversion from strftime to date got php 8

See merge request ispconfig/ispconfig3!1652

Fix undefined variable firewall_server_enabled and xmpp_server_enabled, #6400

See merge request ispconfig/ispconfig3!1653

Fix undefined $postfix_version and generalize code, #6405

Closes #6405

See merge request ispconfig/ispconfig3!1654

Fix undefined $conf, #6406

Closes #6406

See merge request ispconfig/ispconfig3!1655