Originally from:
https://github.com/kubernetes/ingress-nginx/tree/master/images/echoheaders

Moving the code here to prevent bit-rot and to be sure we can recreate
or update the images on demand. Moving it here also ensures we can use
the common harness to build the multi-arch manifests needed for running
the e2e test that use this container.

Change-Id: I15009268da4e7809a1c03d9af3181b585afa8139