Enable Openshift for connect injector

[ishustava]

Companion to hashicorp/consul-k8s#521 and hashicorp/consul-k8s#524
Changes proposed in this PR:

• Pass -enable-openshift flag to connect injector when openshift is enabled globally

How I've tested this PR:
Deployed manually on openshift with the image built from hashicorp/consul-k8s#524 (ishustava/consul-k8s-dev:05-25-2021-0bc1f55)

First, I need to allow Envoy to run as the specific user and the init contianer to run with elevated privileges:

oc adm policy add-scc-to-user anyuid -z default
oc adm policy add-scc-to-user privileged -z default

This will allow any pod with the default service account to run as any user and have elevated privileges to run iptables.

Deployed static-server and static-client with:

---
apiVersion: v1
kind: Service
metadata:
  name: static-server
spec:
  type: LoadBalancer
  selector:
    app: static-server
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: static-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: static-server
  template:
    metadata:
      name: static-server
      labels:
        app: static-server
      annotations:
        "consul.hashicorp.com/connect-inject": "true"
    spec:
      containers:
        - name: static-server
          image: docker.mirror.hashicorp.services/hashicorp/http-echo:latest
          args:
            - -text="hello world"
            - -listen=:8080
          ports:
            - containerPort: 8080
              name: http
      terminationGracePeriodSeconds: 0 # so deletion is quick

apiVersion: v1
kind: Service
metadata:
  name: static-client
spec:
  selector:
    app: static-client
  ports:
    - port: 80
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: static-client
spec:
  replicas: 1
  selector:
    matchLabels:
      app: static-client
  template:
    metadata:
      name: static-client
      labels:
        app: static-client
      annotations:
        "consul.hashicorp.com/connect-inject": "true"
    spec:
      containers:
        - name: static-client
          image: docker.mirror.hashicorp.services/curlimages/curl:latest
          command: [ "/bin/sh", "-c", "--" ]
          args: [ "while true; do sleep 30; done;" ]

$ kubectl exec deploy/static-client -- curl -s static-server
Defaulting container name to static-client.
Use 'kubectl describe pod/static-client-dc7497cb4-5dzkl -n consul' to see all of the containers in this pod.
"hello world"

How I expect reviewers to test this PR:

• code review

Checklist:

• Bats tests added
• CHANGELOG entry added (HashiCorp engineers only, community PRs should not add a changelog entry)

[kschoche]

Looks great!