Add script to allow running CI on community PRs (#6016)

The script can be executed like so:

    ./scripts/run-ci-on-community-pr.sh <pr-id>

It will do the following:

1. Rebase the community PR againt its target branch.
2. Sign all the commits in the community PR.
3. Create a temporary PR to allow running of CI in the community PR.

The temporary PR can be closed once CI has completed running.

Author: watson

scripts/run-ci-on-community-pr.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+PR_ID=${1:-}
+
+if [ -z "$PR_ID" ]; then
+  echo "Usage: $0 <pr-id>"
+  echo
+  echo "This will:"
+  echo "1. Rebase the PR with its target branch, with each contained commit signed."
+  echo "2. Create a temporary PR to allow running CI on the community PR."
+  echo
+  echo "Prerequisites:"
+  echo "- You must have a GPG key configured to use with git."
+  echo "- You must have write access to the PR."
+  echo
+  exit 1
+fi
+
+GITHUB_USER=$(gh api user --jq .login)
+BASE_COMMIT=$(gh pr view $PR_ID --json baseRefOid --jq '.baseRefOid')
+TEMP_BRANCH=$GITHUB_USER/tmp-ci-run-$PR_ID-$(date +%s)
+WORKTREE_DIR=$(mktemp -d)
+ORIGINAL_DIR=$(pwd)
+
+cleanup() {
+  if [ -n "${WORKTREE_DIR:-}" ] && [ -d "$WORKTREE_DIR" ]; then
+    cd "$ORIGINAL_DIR" 2>/dev/null || true
+    git worktree remove "$WORKTREE_DIR" 2>/dev/null || true
+  fi
+}
+
+trap cleanup EXIT ERR INT
+
+git worktree add $WORKTREE_DIR
+cd $WORKTREE_DIR
+
+git fetch origin
+gh pr checkout $PR_ID
+git rebase --gpg-sign $BASE_COMMIT
+git push --force
+git push origin HEAD:$TEMP_BRANCH
+
+gh pr create \
+  --head $TEMP_BRANCH \
+  --draft \
+  --label "semver-patch" \
+  --title "Temp: Run CI on community PR #$PR_ID" \
+  --body "This is a temporary PR to allow running CI on the community PR #$PR_ID. It should be closed after CI has completed running."
+gh pr view $TEMP_BRANCH --web