Ability to do a code review without a Merge Request

Currently, the only way to do a code review is to create a Merge Request. But what about existing code? What we're currently doing is pointing Atlassian Crucible to our git repositories, one at a time. This is painful because we have to ask the Crucible admin for each new repository that we had, and also because Crucible interface is a mess 😺

In essence, the idea is that a code review is great for things that already exist in the repo, not only for additions (in the form of an MR).

Thanks,

Clément