* metadata addon works

* Add code for metadata server image and makefile rules

* remove log message

* update to work with v1.13.11

* update readme

* fix metadata addon stuff for newer codebase

* buncha changes

* just so many changes

* ch-ch-ch-ch-changes

* addon works

* update readme

* boilerplate

* revert unrelated change

* move server code to another repo

* switch addon name to gcp-auth

* metadata -> gcp-auth

* missed one

* automate finding of credentials

* remove unnecessary comment

* address comments

* Update README.md

* Update README.md

* use mustload everywhere

* swap selector condition

* upgrade kube-webhook-certgen to 1.3

* move paths to constants

* add notice to user on addon enable

* adding addon documentation

* move addons documentation inside handbook

* remove old addons docs location
Co-authored-by: NPriya Wadhwa <priyawadhwa@google.com>

This PR adds the code for enabling gvisor in minikube. It adds the pod
that will run when the addon is enabled, and the code for the image
which will run when this happens.

When gvisor is enabled, the pod will download runsc and the
gvisor-containerd-shim. It will replace the containerd config.toml and
restart containerd.

When gvisor is disabled, the pod will be deleted by the addon manager.
This will trigger a pre-stop hook which will revert the config.toml to
it's original state and restart containerd.

Previously we were mixed between the two forms. This commit picks %v,
which is consistent with the Kubernetes code base. They both effectively
do the same thing in this case, though %v works with any object, and %s
only with string objects.