Create a tool to get images that are referenced by resource-dispatcher charm

[NohaIhab]

Description

To be able to integrate mlflow with kubeflow in an airgapped environment, the resource-dispatcher charm should be deployed.
There needs to be a script available to retrieve the image that is deployed by resource-dispatcher charm.
This script will then be used by the airgapped environment script in canonical/bundle-kubeflow#682.
Discussed in canonical/bundle-kubeflow#705 (comment).