feat(kustomize): add TBC envsubst support for Kustomize based deployment

mentioned in commit 0705d3cc

mentioned in merge request to-be-continuous/samples/python-on-kubernetes!80 (merged)

mentioned in merge request to-be-continuous/samples/php-on-kubernetes!124 (merged)

mentioned in merge request to-be-continuous/samples/maven-on-kubernetes!139 (merged)

mentioned in merge request to-be-continuous/samples/golang-cnb-on-kubernetes!74

mentioned in merge request to-be-continuous/samples/php-cnb-on-kubernetes!66 (merged)