CI: Trigger manual actions via API

Description

I have a manual action set up in my CI like the following:

production:
  stage: deploy
  script: run-deployment $OMNIBUS_GITLAB_PACKAGE
  environment: production
  when: manual

I would like to trigger this step via the Gitlab API, but I can't find a way to do that. Is it currently possible?

Proposal

Provide a way to use the Trigger API to trigger manual actions for CI jobs.