Graphic visualization of non `.gitlab-ci.yml` pipeline files
With https://gitlab.com/gitlab-org/gitlab-ce/issues/58606 we allow the preview of files named .gitlab-ci.yml
which we can safely assume will be used as a pipeline. This issue is a follow up to that to say: can we use the structure of a generic ``yml` file to assume that it is for use in a pipeline?
In other worse, if a yml file substantially follows our yaml specification for .gitlab-ci.yml, enable the "Preview pipeline" button in the WebIDE