GitLab API - Pre-confirm accounts

Created by: jbrooksuk

We're using the API to generate a GitLab account for each user within our internal CRM. They never need to know about this since we're simply asking them for the content (we're generating the title) and posting it as an issue.

During testing of user creation, apart from #6878 (closed), the API should be able to be able to bypass the confirmation email, so that they don't know about it.