feat(GlModal): Allow no autofocus on show

mentioned in commit 1dc07ef1

mentioned in merge request status-page!593 (merged)

mentioned in merge request gitlab!93864 (merged)

mentioned in merge request gitlab!95273 (closed)

mentioned in merge request gitlab-docs!3023 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3011 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!87 (merged)