chore: Add action to send PRs and issues to internal slack (aws#8607)

* Add workflow to send new PRs and issues to internal slack

* add notify slack action

Author: seshubaws

.github/workflows/notify-slack.yml

@@ -0,0 +1,33 @@
+name: Slack Notifications
+
+on:
+  pull_request:
+    types: [labeled]
+  issues:
+    types: [opened]
+
+jobs:
+  notify-slack:
+    runs-on: ubuntu-latest
+    if: (github.event_name == 'pull_request' && github.event.label.name == 'pr/external') || github.event_name == 'issues'
+    permissions:
+      contents: read
+    steps:
+      - name: Send External PR Notification
+        if: github.event_name == 'pull_request'
+        uses: rtCamp/action-slack-notify@e31e87e03dd19038e411e38ae27cbad084a90661 # v2
+        env:
+          SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK_URL }}
+          SLACK_TITLE: 'PR Created: ${{ github.event.pull_request.title }} by ${{ github.event.pull_request.user.login }}'
+          SLACK_FOOTER: ''
+          MSG_MINIMAL: true
+          SLACK_MESSAGE: '${{ github.event.pull_request.html_url }}'
+      - name: Send New Issue Notification
+        if: github.event_name == 'issues'
+        uses: rtCamp/action-slack-notify@e31e87e03dd19038e411e38ae27cbad084a90661 # v2
+        env:
+          SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK_URL }}
+          SLACK_TITLE: 'Issue Created: ${{ github.event.issue.title }} by ${{ github.event.issue.user.login }}'
+          SLACK_FOOTER: ''
+          MSG_MINIMAL: true
+          SLACK_MESSAGE: '${{ github.event.issue.html_url }}'