feat(CSS): add `gl-sm-justify-content-start` utility CSS class

mentioned in commit fe64ca6b

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!186 (merged)

mentioned in merge request status-page!862 (merged)

mentioned in merge request gitlab!129862 (closed)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!197 (merged)

mentioned in merge request gitlab!130154 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3432 (merged)

mentioned in merge request gitlab-docs!4196 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3508 (merged)

mentioned in merge request gitlab-docs!4197 (merged)

mentioned in merge request gitlab-docs!4198 (closed)