storage/kubernetes: Removing Kubernetes TPR support

Third Party Resources (TPR) have been removed from Kubernetes for
roughly 2 years.  This commit removes the support dex had for them.

Documentation has been updated to reflect this and to instruct users
on how to migrate from TPR-powered dex environment to a Custom Resource
Defintion (CRD) based one that dex > v2.17 will support

scripts/dump-tprs

@@ -1,13 +0,0 @@
-#!/bin/bash
-
-set -e
-
-if [ -z $DEX_NAMESPACE ];then
-        echo "Must export \$DEX_NAMESPACE"
-        exit
-fi
-
-for RESOURCE in authcodes authrequests connectors oauth2clients offlinesessionses refreshtokens passwords signingkeies; do
-        kubectl get --namespace=$DEX_NAMESPACE $RESOURCE.oidc.coreos.com  -o yaml
-done
-