all builders should be able to reference IMAGE from templated fields.

[ericzzzzzzz]

Information

• Skaffold version: v2.6.0
• Operating system: all
• Installed via: source
• Some background is here : https://kubernetes.slack.com/archives/CABQMSZA6/p1691756377332849
• The IMAGE variable is image reference that skaffold created in tagging stage, that variable is already available for setting up custom builder, https://skaffold.dev/docs/builders/builder-types/custom/
• We should make this behavior consistent across all builders, the custom builder also able to access other variables, like $PUSH_IMAGE, $PLATFORMS , we may make the same change for those vars as well.