Adds GH action to sync branches

Author: frenzyfriday

.github/workflows/sync_branches_manually.yml

@@ -0,0 +1,13 @@
+---
+name: Github Action to trigger downstream job
+on:
+  issue_comment:
+    types: [created, edited]
+
+jobs:
+  trigger_sync:
+    if: contains(github.event.comment.body, '/sync-olive')
+    uses: openstack-k8s-operators/ci-framework/.github/workflows/sync_branches_reusable_workflow.yml@main
+    with:
+      main-branch: main
+      follower-branch: olive

.github/workflows/sync_branches_periodically.yml

@@ -0,0 +1,13 @@
+---
+name: Github Action to trigger downstream job
+on:
+  schedule:
+    - cron: '0 1 * * 4'
+
+jobs:
+  trigger_sync:
+    if: contains(github.event.comment.body, '/sync-olive')
+    uses: openstack-k8s-operators/ci-framework/.github/workflows/sync_branches_reusable_workflow.yml@main
+    with:
+      main-branch: main
+      follower-branch: olive

.github/workflows/sync_branches_reusable_workflow.yml

@@ -0,0 +1,32 @@
+---
+name: Sync Olive branch with Main
+on:
+  workflow_call:
+    inputs:
+      main-branch:
+        required: true
+        type: string
+      follower-branch:
+        required: true
+        type: string
+
+jobs:
+  sync:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Update the follower branch
+        run: |
+          git checkout ${{ inputs.main-branch }}
+          git fetch origin
+          git checkout ${{ inputs.follower-branch }}
+          git pull
+          git rebase origin/${{ inputs.main-branch }}
+          git push origin ${{ inputs.follower-branch }}