Add Makefile targets to build all-in-one Operator manifest

Instead of Makefile targets that directly kubectl apply ... the output of kustomize build to stdout, introduce 2-stage process with intermediate stage that produces the all-in-one YAML manifest that can be published and used by our customers instead of having to follow the fairly involved process of building said manifests themselves (and relying on tools to be installed locally).

Closes #204 (closed)