Add support for k8s pod to node affinity and taint toleration (#917)

Reviewed-on: cerc-io/stack-orchestrator#917
Reviewed-by: Thomas E Lackey <telackey@noreply.git.vdb.to>
Co-authored-by: David Boreham <david@bozemanpass.com>
Co-committed-by: David Boreham <david@bozemanpass.com>

stack_orchestrator/constants.py

@@ -35,5 +35,7 @@ security_key = "security"
 annotations_key = "annotations"
 labels_key = "labels"
 replicas_key = "replicas"
+node_affinities_key = "node-affinities"
+node_tolerations_key = "node-tolerations"
 kind_config_filename = "kind-config.yml"
 kube_config_filename = "kubeconfig.yml"