New `arch` config.cfg parameter is used along with the image name
parameter to find the most recent OS image to be used in hosted ec2
instance. This allows the user to choose arm based instance types
which was causing algo failure during cloud formation.
If new instance_market_type config.cfg variable specifies 'spot' instead of 'on-demand' then
the stack.yml creates a LaunchTemplate resource using spot option. The create EC2 Instance command
uses that LaunchTemplate.
