Add two-way reference field component

[Jamiewarb]

You can create a relationship field on one document type to point to another document type. However you then have to remember which way round the fields are.

As a contrived example, blog articles may have authors. You open an article to add authors to it. But if you open an author, you can't add or remove articles to it.

The current solution is to show Backlinks, so that you can see what articles are tagged with this author, then visit the article to change it.

For blog articles, this is okay, but it's not always ideal for some content structures.

Instead, we'd like to create a component that can handle two-way relationships, keeping one in sync whenever the other changes.

In the example above, this would allow Authors to have an Articles relationship, and add/remove articles as well, keeping the list on the articles updated at the same time.