Please add 'sleep' command to all 'from scratch' images to enable Image Puller

We have a customer making Disaster Recovery preparations.  They want to be assured they will not be affected if the Red Hat Registry should become available.

Part of the preparation is use of the Image Puller, to place needed images on local nodes.  (In the hopes that the Red Hat Registry being lost will not affect the cluster.)

The customer has noted that some images do not work with the Image Puller, as described in our documentation [1]:

"The minimal requirement for an image to be pre-pulled is the availability of the sleep command, which means that FROM scratch images (for example, 'che-machine-exec') are currently not supported."

Please add 'sleep' to these images or make some other allowance so the DR scheme is viable.

[1]  https://access.redhat.com/documentation/en-us/red_hat_codeready_workspaces/2.5/html-single/administration_guide/index#caching-images-for-faster-workspace-start_crw