Add virtualbox-iso target

Lots of other, small quality of life improvements to build process
Output of build serial console to artifacts upon failure
Reducing verbosity of Packer, now that serial output is captured
Fixed sizing problems with the boot partitions of Ubuntu versions
Use of Mac builders for Virtualbox targets
Updating Ubuntu builders to 22.04, as well

scripts/minimize.sh

@@ -6,12 +6,12 @@ set -x
 rm -rf /home/vagrant/.ansible
 sudo rm -rf /root/.ansible
 
-#if [[ "${PACKER_BUILD_NAME}" != *"silverblue"* ]]; then
+if [ ! -e /etc/fedora-release ]; then
 	sudo dd if=/dev/zero of=/var/EMPTY bs=1M || :
 	sync
 	sudo rm /var/EMPTY
 	sync
-#fi
+fi
 
 # In CentOS 7, blkid returns duplicate devices
 swap_device_uuid=`sudo /sbin/blkid -t TYPE=swap -o value -s UUID | uniq`