Adds validate_manifest_images_exist() to DockerSyncImagesKeywords. This
keyword checks that all images listed in a manifest YAML file are
present in the local Docker registry (e.g., registry.local:9001). It is
intended to be called after syncing images using sync_images_from_manifest().
Missing images trigger a KeywordException by default. An optional
fail_on_missing flag allows non-blocking validation with a boolean
return value for scripting or diagnostics.
Change-Id: I1b9b8165897827329d0b17b7e4a401195c53c2e8
Signed-off-by: Andrew Vaillancourt <andrew.vaillancourt@windriver.com>
edd63dbab2