Support for additional IAM policies

[stephenmsachs]

Users are able to add any additional IAM policies into the text box, but the cluster creation will fail in most cases. This comes from a limitation in the template for ParallelCluster API. The DefaultParallelClusterIamAdminPolicy defined here is used to build pcluster-manager.

[mendaomn]

Can you provide an example policy that would make the cluster creation fail?

[stephenmsachs]

Can you provide an example policy that would make the cluster creation fail?

arn:aws:iam::aws:policy/AmazonS3FullAccess