Build with Ubuntu 22.04.4, do not wait for network on boot

Typically the Abitti server is itself the DHCP server for Abitti clients. In the exam network there is no DHCP servers and the regular Ubuntu Server requires response from DHCP to boot. This pull request makes following changes:

• Masks (makes ineffective) two systemd targets (NetworkManager and systemd-networkd) waiting network on boot.
• Remove open-iscsi package which requires network access on boot.
• Remove systemd-networkd-dispatcher as NetworkManager is used to control the network.
• A new script ytl-linux-purge-deb executed by cron on boot. The script removes named deb packages on boot, if installed. This is used to remove the aforementioned open-iscsi and

Install image was updated to Ubuntu 22.04.04

Build with Ubuntu 22.04.3

• Install Ubuntu 22.04.03 instead of 20.04
• Install Firefox as snap instead of .deb
• Upgraded Oracle VirtualBox from 6.1 to 7.0
• Upgraded GitHub Actions scripts
• New version numbering scheme

Build with Ubuntu 20.04.2

v0.4

Updated Ubuntu image version to 20.04.2

Remove boot timeout

Remove boot timeout from YTL Linux installation media to avoid boot loop. In other words the boot starts only by pressing enter to the grub menu.