Make related issues components reusable
This merge request moves some of the Related Issues components to vue_shared folder and updates naming to make them reusable for upcoming Related Merge Requests widget.
Related Issues is a EE only feature and it has some extra EE-only components like weight and due-date information. However Related Merge Requests widget will be available in CE too, in other words, not-EE specific.
To be able to reuse those components on the CE side, I moved them to
vue_shared folder and will also create another merge request which will c/p them to CE/vue_shared and then start refactoring Related Merge Requests widget using Vue.
This MR shouldn't break anything since it's just some file structure and naming change.