[FEATURE] Automate custom AMI creation

[cartalla]

Is your feature request related to a problem? Please describe. Automate the creation of custom compute node AMIs that have the configured customizations already done.

Describe the solution you'd like Create EC2 image build pipeline that

• Starts with ParallelCluster AMI
• Configures custom file system mounts
• Configures default users and groups
• Installs EDA packages

It might make sense for this to be a completely different stack that is created before the cluster so that the AMIs are available to configure the cluster.

[cartalla]

Added generation of config files and documentation on how to use them.