Validation tests for sync scripts between up and mid/downstream repos

In today's prioritization call, Mario pointed out a gap we have in our upstream-to-downstream sync scripts: they're not supported by tests, so sometimes regressions sneak into the downstream repos when the sed/perl/yq/jq transformations are applied.

Affected scripts include:

• codeready-workspaces-chectl/build/scripts/sync-chectl-to-crwctl.sh
• codeready-workspaces-operator/build/scripts/sync-che-olm-to-crw-olm.sh
• codeready-workspaces-operator/build/scripts/sync-che-operator-to-crw-operator.sh

• codeready-workspaces/Jenkinsfile
• che-plugin-registry
• che-devfile-registry
• traefik
• che-machine-exec
• che-editor-intellij-community
• kubernetes-image-puller
• che-jwtproxy
• configbump
• che-pluginbroker

Another aspect of this is validating that the digests in the registries are the same as those in the metadata/CSV, and notifying if this is not the case when the metadata is built.
But if CRW-1157 is fixed, we might no longer have digests in the registries, and at least avoid having problems like CRW-2112 occur.

We could also do content verification once images are built, eg.,

podman run -it --rm --entrypoint /bin/bash quay.io/crw/theia-rhel8:2.10 -c "grep eclipse-che/plugin  ~/package.json"
    "@eclipse-che/plugin": "7.32.2",