Add Google Cloud K3s infrastructure support

- Add Terraform configuration for GCP instance and storage
- Add startup script for K3s installation and configuration
- Add pipeline scripts for deployment and management
- Add Forgejo deployment manifests and configuration

gcloud/tf/k3s/forgejo/issuer.yaml.template

@@ -0,0 +1,17 @@
+apiVersion: cert-manager.io/v1
+kind: Issuer
+metadata:
+  name: le-cluster-issuer-http
+  namespace: forgejo
+spec:
+  acme:
+    email: ${EMAIL}
+    # We use the staging server here for testing to avoid throttling.
+    server: https://acme-staging-v02.api.letsencrypt.org/directory
+    # server: https://acme-v02.api.letsencrypt.org/directory
+    privateKeySecretRef:
+      name: http-issuer-account-key
+    solvers:
+      - http01:
+          ingress:
+            class: traefik