Adding vdev support and vfio

Adding vdev support and vfio

Using vfio in stead of igb_uio. DPDK 2020.5 is NOT compiling the igb_uio
driver by default any more.
For the l3 mode, we are now using the new PROX vdev feature. This is
achieved by adding the vdev parameter in the port section of the PROX
config files. One of the advantages is that we can now ping a port
managed by PROX: the requests will be forwarded by PROX to the LINUX
stack, who will reply to the ping. A tap device is being created by PROX
to support this feature.
Installing old version of nasm since latest causes some issues.
If not pushgateway is being used, it should be commented out in the
config_file.
vfio is now loaded by specifying the module in /etc/modules-load.d
There is also an after_boot.sh script that will be run by
check_prox_system_setup.sh, which can be used for further configuration
of the instance after boot.
There is now also a file created /opt/rapid/system_ready_for_rapid by
the check_prox_system_setup.sh script. This file is created once all
configuration is done. The runrapid.py script will wait till this file
is created before executing any tests.

Change-Id: Ic5c41af82642066af42134c3323297f5a06f6f72
Signed-off-by: Luc Provoost <luc.provoost@intel.com>