feat: new workflow to detect PR edit and trigger renovate scan

This commit,
1. ensures PR body edit contains Rebase Tick Box is ticked
2. validates PR author is renovate bot or not
3. trigger renovate scan using composite action from
BitGo/gha-renovate-bot

Ticket: DO-4550

.github/workflows/pull-request-edit.yaml

@@ -0,0 +1,31 @@
+name: on_pr_edit
+run-name: 'on_pr_edit: ${{ github.ref_name }}'
+
+on:
+  pull_request:
+    types:
+      - edited
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  id-token: write
+  contents: read
+
+jobs:
+  run-scan:
+    name: Trigger Renovate Scan
+    if:
+      ${{ contains(github.event.pull_request.body, '[x] <!-- rebase-check -->')
+      && github.event.pull_request.user.login == 'bitgo-renovate-bot[bot]' }}
+    runs-on: ubuntu-latest
+    steps:
+      - id: trigger-renovate-scan
+        uses: BitGo/gha-renovate-bot@master
+        with:
+          target-base-branch: master
+          target-repository: ${{ github.repository }}
+          caller-pr: ${{ github.event.pull_request.number }}
+          trigger-token: ${{ secrets.BITGOBOT_RENOVATE_ACTIONS_GITHUB_TOKEN }} # Should be a PAT