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-repo-server-vault-ca-patch.yaml

@@ -0,0 +1,25 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: argocd-repo-server
+  namespace: argocd
+spec:
+  template:
+    spec:
+      volumes:
+        - name: vault-ca-cert
+          secret:
+            secretName: vault-ca-cert
+            items:
+              - key: ca.crt
+                path: ca.crt
+      containers:
+        - name: argocd-repo-server
+          env:
+            - name: SSL_CERT_DIR
+              value: /etc/ssl/certs:/custom-certs
+          volumeMounts:
+            - name: vault-ca-cert
+              mountPath: /custom-certs
+              readOnly: true