Add any_approver option for gitlab_project_approval_rule

Created by: petrmvala

Feature Description

This is a part of GitLab API. Setting approval_rule = "any_approver" enables setting the Eligible approvers in the project, enabling for the proper use of the CODEOWNERS file.

It is currently blocked in the go-gitlab library, but that should be fixed with this PR:

• https://github.com/xanzy/go-gitlab/pull/1396

Do you want to implement this?

• I would like to implement this myself 👷