Add oauth-cabundle configmap to bundle mount

[nrfox]

Turns the cabundle configmap volume into a projected volume and adds the optional oauth-cabundle configmap to the mount.

To test:

1. Deploy Kiali on openshift
2. Create an oauth-cabundle configmap:

   kubectl create configmap -n istio-system kiali-oauth-cabundle --from-literal=oauth-server-ca.crt=somecrt
   

3. Restart Kiali pod

   kubectl rollout restart deployment -n istio-system kiali
   kubectl rollout status deployment -n istio-system kiali
   

4. Ensure file exists on the kiali pod at: /kiali-cabundle/oauth-server-ca.crt

   kubectl exec -it -n istio-system deployments/kiali -- cat /kiali-cabundle/oauth-server-ca.crt
   > somecrt
   

Server PR: kiali/kiali#7974
Docs PR: kiali/kiali.io#838

[jmazzitelli]

Normal deployment of kiali using typical make build build-ui test cluster-push operator-create kiali-create (this is done without creating the special configmap - I want to see if the deployment works just doing it normally without the special configmap):

$ kubectl exec -it -n istio-system deployments/kiali -- ls /kiali-cabundle
service-ca.crt

I then create the configmap per test instructions, do a rollout restart of the kiali deployment, and then look in the directory again:

$ kubectl exec -it -n istio-system deployments/kiali -- ls -1 /kiali-cabundle
oauth-server-ca.crt
service-ca.crt

The content is as expected:

$ kubectl exec -it -n istio-system deployments/kiali -- cat /kiali-cabundle/oauth-server-ca.crt
somecrt

$ kubectl exec -it -n istio-system deployments/kiali -- cat /kiali-cabundle/service-ca.crt
-----BEGIN CERTIFICATE-----
...[chomp]...
-----END CERTIFICATE-----