Fix some packer warnings/notices in the templates

[timschumi]

• Fixed some duplicate keys in the magma-hyperv template
• ssh_wait_timeout has been deprecated in favor of ssh_timeout
• disk_size is now expected to be a string for QEMU builds
• Print the currently validating file in the helper script

[timschumi]

The first three commits were made by hand.

The ssh_timeout commit is made using the following command:

sed -i 's/ssh_wait_timeout/ssh_timeout/g' *.json

The disk_size commit is made using the following command:

sed -i 's/"disk_size": \([[:digit:]]\+\)/"disk_size": "\1"/g' *-libvirt.json *-docker.json *-libvirt-x32.json

[timschumi]

Everything is merged/picked by now.