feat: comment URL on previewed PRs (#16085)

.github/workflows/preview-comment.yaml

@@ -0,0 +1,17 @@
+name: Preview comment
+
+on:
+  pull_request:
+    types: [labeled]
+
+jobs:
+  comment-status:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.label.name == 'preview' }}
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: mshick/add-pr-comment@v2
+        with:
+          message-id: "preview-status"
+          message: "Deploying preview environment to https://pr-${{ github.event.pull_request.number }}.preview.internal.immich.cloud/"