TLS: with static certificates

[kylehodgetts]

This PR closes #33

Changes

Adds support for specifying TLS options in an EnvoyFleet

• an array of CipherSuites
• TLS min and max versions
• an array of cert and key pairs

Testing

• make create-env
• Wait for everything to become healthy (ensure cert-manager is installed)
• Apply issuer.yaml and certificate.yaml (below)
• Uncomment TLS and tlsSecrets options in the default EnvoyFleet. Leave cipherSuites and min/max versions commented out.
• Reapply kubectl apply -f config/samples/gateway_v1_envoyfleet.yaml
• Install the TODOMVC application
• Hit the application on HTTPS

issuer.yaml

kubectl apply -f - <<EOF
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: test-selfsigned
  namespace: default
spec:
  selfSigned: {}
EOF

certificate.yaml

kubectl apply -f - <<EOF
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: my-cert
  namespace: default
spec:
  dnsNames:
    - todomvc.com
  secretName: my-cert
  issuerRef:
    name: test-selfsigned
EOF

Checklist

• tested locally
• added new dependencies
• updated the docs
• added a test