Dual-write ENC data into encapi alongside Cobbler

Seed encapi (statuses, roles, prodnxsr node assignments) and make the
instance module also create an encapi_node for every VM, so the k8s
puppetserver ENC can cut over from Cobbler. Cobbler/puppetca/puppetdb
resources are left untouched.

- Add config/encapi leaf + modules/encapi driving statuses/roles/nodes
  from YAML (3 statuses, 51 roles, 13 prodnxsr physical nodes).
- Add encapi_node to modules/instance (certname, role, environment).
- Wire encapi provider into root.hcl required_providers and the module
  providers; plumb ENCAPI_WRITE_TOKEN via Makefile vault_env.

modules/instance/providers.tf

@@ -17,3 +17,8 @@ provider "puppetca" {
   cert = var.puppet_cert_pub
   key  = var.puppet_cert_priv
 }
+
+provider "encapi" {
+  endpoint = var.encapi_endpoint
+  # token defaults to the ENCAPI_WRITE_TOKEN environment variable
+}