[DEVELOPER-5288] Compose field widget
JIRA issue
https://issues.jboss.org/browse/DEVELOPER-5288
Testing instructions
- Go here: http://localhost:8888/admin/structure/types/manage/article/form-display and verify that you can add the Compose - Complex field widget to the Content field
- Go edit any Article (or create an Article) and verify that the widget functionality of the Content field is exactly the same as it currently is on 8.x-1.x, which is currently using the IEF - Complex widget
Technical details
This FieldWidget just extends the IEF- Complex FieldWidget class. It is really simple, in code, actually and most of the work in this ticket was discovery for follow up tickets that will require AJAX modal forms, editing/modifying some of the entity forms, modifying some of the submit/links/buttons and also changing the 'preview' functionality of the referenced entities.