Leverage helm-based install and simplify manifests

[andrewstucki]

This simplifies much of the tutorial to leverage helm instead of using the kustomize-based installation method. Tested with:

kind create cluster --config=kind/cluster.yaml
kubectl apply -k "github.com/hashicorp/consul-api-gateway/config/crd?ref=v0.1.0-beta"
helm install --values consul/config.yaml consul hashicorp/consul --version "0.40.0"
kubectl apply -f two-services
kubectl apply -f api-gw/consul-api-gateway.yaml
kubectl wait --for=condition=ready gateway/example-gateway --timeout=90s && kubectl apply -f api-gw/routes.yaml

[nathancoleman]

Instructions work for me:

❯ kubectl get pods
NAME                                             READY   STATUS    RESTARTS   AGE
consul-api-gateway-controller-5c46947749-gn24l   1/1     Running   1          93s
consul-client-l9rln                              1/1     Running   0          93s
consul-connect-injector-5c6557976b-2kg26         1/1     Running   0          93s
consul-connect-injector-5c6557976b-lckbv         1/1     Running   0          93s
consul-controller-84b676b9bb-6jfjf               1/1     Running   0          93s
consul-server-0                                  1/1     Running   0          93s
consul-webhook-cert-manager-8595bff784-bvg7n     1/1     Running   0          93s
echo-1-79b597d656-8q8fq                          2/2     Running   0          66s
echo-2-94b68d65b-z7x85                           2/2     Running   0          65s
example-gateway-79488ff7dd-45tk4                 1/1     Running   0          20s
frontend-5c54674c4-6lfq8                         2/2     Running   0          65s
payments-77598ddb8f-vvrj6                        2/2     Running   0          64s
postgres-8479965456-2xl6p                        2/2     Running   0          64s
product-api-dcf898744-fjz5h                      2/2     Running   0          64s
public-api-7f67d79fb6-hxb6b                      2/2     Running   0          63s