chore: mount vault CA for helm TLS trust and add ArgoCD self-management (#112)

- Patch argocd-repo-server to mount vault-ca-cert and set SSL_CERT_DIR
  so helm subprocesses trust the internal CA when pulling charts
- Add argocd Application pointing at clusters/au-syd1/bootstrap so
  ArgoCD manages its own install going forward

Reviewed-on: #112

clusters/au-syd1/bootstrap/argocd-self-app.yaml

@@ -0,0 +1,21 @@
+---
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: argocd
+  namespace: argocd
+spec:
+  project: default
+  source:
+    repoURL: https://git.unkin.net/unkin/argocd-apps
+    targetRevision: HEAD
+    path: clusters/au-syd1/bootstrap
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: argocd
+  syncPolicy:
+    automated:
+      prune: false
+      selfHeal: true
+    syncOptions:
+      - ServerSideApply=true