replace "dep" with "go mod"

A simple "go mod init && go mod tidy && go mod vendor" was enough and
mostly seems to have picked the same revisions of the dependencies as
before. Notable exceptions are klog and gogo/protobuf.

vendor/k8s.io/code-generator/README.md

@@ -1,24 +0,0 @@
-# code-generator
-
-Golang code-generators used to implement [Kubernetes-style API types](https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md).
-
-## Purpose
-
-These code-generators can be used
-- in the context of [CustomResourceDefinition](https://kubernetes.io/docs/tasks/access-kubernetes-api/extend-api-custom-resource-definitions/) to build native, versioned clients,
-  informers and other helpers
-- in the context of [User-provider API Servers](https://github.com/kubernetes/apiserver) to build conversions between internal and versioned types, defaulters, protobuf codecs,
-  internal and versioned clients and informers.
-
-## Resources
-- The example [sample controller](https://github.com/kubernetes/sample-controller) shows a code example of a controller that uses the clients, listers and informers generated by this library.
-- The article [Kubernetes Deep Dive: Code Generation for CustomResources](https://blog.openshift.com/kubernetes-deep-dive-code-generation-customresources/) gives a step by step instruction on how to use this library.
-
-## Compatibility
-
-HEAD of this repo will match HEAD of k8s.io/apiserver, k8s.io/apimachinery, and k8s.io/client-go.
-
-## Where does it come from?
-
-`code-generator` is synced from https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/code-generator.
-Code changes are made in that location, merged into `k8s.io/kubernetes` and later synced here.