chore: implement script for back porting (#15635)

backport.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+# Usage: ./backport.sh 'feature/im-play-nightly' 47bc4b2ade1baffbb6693ae149bca6126c2f352e 2.40 2.39 2.38 2.37
+
+set -euo pipefail
+
+if ! git diff --cached --exit-code; then
+  echo "Nothing should be staged when running this script."
+  exit 1
+fi
+
+if ! command -v git &> /dev/null; then
+  echo "git could not be found."
+  exit 1
+fi
+
+if ! command -v gh &> /dev/null; then
+  echo "gh could not be found."
+  exit 1
+fi
+
+if [[ -z "${1:-}" ]]; then
+  echo "No base branch specified."
+  exit 1
+fi
+base_branch="$1"
+
+if [[ -z "${2:-}" ]]; then
+  echo "No commit specified."
+  exit 1
+fi
+commit="$2"
+
+shift 2
+
+if [[ -z "${*:-}" ]]; then
+  echo "No backport branches specified."
+  exit 1
+fi
+
+pr_id=$(gh pr list --search "$commit" --state merged --head "$base_branch" --json number --jq '.[0].number')
+pr_url=$(gh pr view "$pr_id" --json url --jq '.url')
+pr_title=$(gh pr view "$pr_id" --json title --jq '.title')
+pr_reviewer=$(gh pr view "$pr_id" --json reviews --jq '.reviews | map(.author.login) | join(",")')
+
+current_branch=$(git branch --show-current)
+
+branches=("$@")
+for branch in "${branches[@]}"; do
+  git checkout "$branch"
+  git pull origin "$branch"
+  git checkout -b "${base_branch}_${branch}"
+  git cherry-pick "$commit"
+  git push origin "${base_branch}_${branch}"
+  gh pr create --head "${base_branch}_${branch}" --base "$branch" --title "backport: $pr_title" --body "$pr_url" --reviewer "$pr_reviewer"
+  # clean up
+  git checkout "$current_branch"
+  git branch -D "${base_branch}_${branch}"
+done