Add 'ready' and 'review' aliases for the 'request_review' command

What does this MR do and why?

• Going forward, we'll document the ready command (see gitlab-org/gitlab!88947 (merged)).
• For back-compatibility we keep request_review.
• For simplicity, we also allow review.

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review

Related to #1020 (closed).