REST API endpoints for adding/removing group CA for a top-level group

Overview

More information about the motivation in epic: Add support for git access control via SSH cert... (&10662 - closed)

Proposal

It should be possible for a group admin (users that can change group settings) to list/add/remove group CA via REST API.

• GET /api/v4/groups/:id/ssh_certificates lists all certificates created for a group

• POST /api/v4/groups/:id/ssh_certificates

  The endpoint should accept key (public key of CA), title (an arbitrary name for the key) and create Groups::SshCertificate record on a top-level group. The app/services/groups/ssh_certificates/create_service.rb can be extracted from Draft: Support uploading CA files to a group (!126741 - closed). If the group is not a top-level group, the request is rejected (400 or 422). Let's also put this functionality behind a feature flag, so we could release it along with other functionality related to SSH certificates.

• DELETE /api/v4/groups/:id/ssh_certificates/:ssh_certificate_id should delete the record. A separate service class may be defined but it's not necessary since it's as simple as certificate.destroy

Availability and Testing

Add new specs for new GET, POST and DELETE endpoints under ee/spec/requests/groups.