Create action file for blog staging deploy (#4560)

fixes #[issue number] 
<!-- Link to relevant issue (for ex: "fixes #1234") which will
automatically close the issue once the PR is merged -->

## PR Type
<!-- Please uncomment one ore more that apply to this PR -->

<!-- - Bugfix -->
<!-- - Feature -->
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
Build or CI related changes
<!-- - Documentation content changes -->
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## Describe the new behavior?
Staging pipeline for blog

## PR Checklist

- [x ] Test: run `npm run test` and ensure that all tests pass
- [x ] Target main branch (or an appropriate release branch if
appropriate for a bug fix)
- [x ] Ensure that your contribution follows [standard accessibility
guidelines](https://docs.microsoft.com/en-us/microsoft-edge/accessibility/design).
Use tools like https://webhint.io/ to validate your changes.


## Additional Information

.github/workflows/blog-preview.yml

@@ -0,0 +1,52 @@
+name: Blog Preview CI/CD
+
+on:
+  push:
+    branches:
+      - staging
+    paths:
+      - "apps/blog/**"
+  pull_request:
+    types: [opened, synchronize, reopened, closed]
+    branches:
+      - staging
+    paths:
+      - "apps/blog/**"
+  workflow_dispatch:
+    branches:
+      - staging
+
+jobs:
+  build_and_deploy_job:
+    if: github.event_name == 'push' || (github.event_name == 'pull_request' && github.event.action != 'closed')
+    runs-on: ubuntu-latest
+    name: Build and Deploy Job
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Build And Deploy
+        id: builddeploy
+        uses: Azure/[email protected]
+        with:
+          azure_static_web_apps_api_token: ${{ secrets.BLOG_PREVIEW_TOKEN }}
+          repo_token: ${{ secrets.GITHUB_TOKEN }} # Used for Github integrations (i.e. PR comments)
+          action: "upload"
+          ###### Repository/Build Configurations - These values can be configured to match your app requirements. ######
+          # For more information regarding Static Web App workflow configurations, please visit: https://aka.ms/swaworkflowconfig
+          app_location: "apps/blog/" # App source code path
+          api_location: "api" # Api source code path - optional
+          output_location: "dist" # Built app content directory - optional
+          ###### End of Repository/Build Configurations ######
+
+  close_pull_request_job:
+    if: github.event_name == 'pull_request' && github.event.action == 'closed'
+    runs-on: ubuntu-latest
+    name: Close Pull Request Job
+    steps:
+      - name: Close Pull Request
+        id: closepullrequest
+        uses: Azure/[email protected]
+        with:
+          azure_static_web_apps_api_token: ${{ secrets.BLOG_PREVIEW_TOKEN }}
+          action: "close"