feat: add terraform_vault role (#127)

this adds a service account that can be used to run the terraform_vault
workflows with, so that we can access the jwt to generate a token

Reviewed-on: #127

apps/base/woodpecker/serviceaccount_terraform_vault.yaml

@@ -0,0 +1,6 @@
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: terraform_vault
+  namespace: woodpecker