Let any GitLab user assign issues to themselves

Problem to solve

It is a problem to find unassigned issues in a big repository, with thousands of them.

Intended users

Any contributor looking to issues to work on.

Further details

A very efficient workflow for big projects with thousands of issues and contributors is contributors looking for unassigned issues to work on, then assign to themselves so nobody else works in them. I'm thinking on moving a big open source project to GitLab, but for what I could see, only members of the organization can assign tickets to themselves, and not any GitLab user. I don't see a setting to change that.

Proposal

Let anyone assign tickets to themselves. A setting that this is only true for projects that opt-in is probably a good idea.

Permissions and Security

Maintainers should be able to decide whether they want to allow that any GitLab user is able to assign issues to themselves.

~feature