chore: add workflow for handling discussions (#26138)

This would add workflow for handling Q & A discussions.

> [CONTRIBUTING GUIDE]: https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md
> [DESIGN GUIDELINES]: https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md

Closes #<issue number here>.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: khushail

.github/workflows/handle-stale-discussions.yml

@@ -0,0 +1,16 @@
+name: HandleStaleDiscussions
+on:
+  schedule:
+    - cron: '0 */4 * * *'
+  discussion_comment:
+    types: [created]
+
+jobs:
+  handle-stale-discussions:
+    name: Handle stale discussions
+    runs-on: ubuntu-latest
+    steps:
+      - name: Stale discussions action
+        uses: aws-github-ops/handle-stale-discussions@v1
+        env:
+          GITHUB_TOKEN:  ${{secrets.GITHUB_TOKEN}}