Description of problem:
When the user runs:

openshift-install agent create image --dir cluster-manifests

But the manifests are either not in cluster-manifests or are missing, the error code generated by the tool leads users to believe that they are missing some tool dependency:

ERROR failed to write asset (Agent Installer ISO) to disk: image reader not available

Version-Release number of selected component (if applicable):4.11.0

How reproducible: 100%

Steps to Reproduce:
1. rm -fr /tmp/cluster-manifests && mkdir /tmp/cluster-manifests
2.openshift-install agent create image --dir cluster-manifests

Actual results:
ERROR failed to write asset (Agent Installer ISO) to disk: image reader not available

Expected results:
Error: Missing manifets in the specified cluster manifest directory: "/tmp/cluster-manifests"

Additional info: