Add an option to enable etcd on the root Tenant #84

The role can turn on ingress for the root Tenant, but not etcd, so an install made with it cannot run tenant Kubernetes clusters until someone patches the root Tenant by hand. Kamaji needs a DataStore, and the root tenant only gets one with spec.etcd: true.

Today roles/cozystack/tasks/main.yml patches {"spec":{"ingress":true}} behind cozystack_tenant_root_ingress. I'd add a cozystack_tenant_root_etcd knob next to it that also sets etcd: true. Defaulting it to true on the isp-full variants makes sense, since they ship the iaas bundle.

Without etcd the failure is silent: the cluster's HelmRelease is Ready and the control plane never appears. That part is tracked in cozystack/cozystack#4783.