Bring back 3.x auto save changes in the Editor form

[HaitingHuang]

In JavaScript API 3.x, the edit changes in the JavaScript API Editor widget are automatically saved whenever the form fields lose focus.
In JavaScript API 4.x, the attributes edit changes in the Editor are only being saved when user clicks the Update button. It's good change if it does not involve attachments in the Editor form. However, users were so got used to 3.x Editor forms that they go ahead adding or updating the attachments before click the update button to save the attributes changes, only to find that the attribute changes have been lost after done with the attachments. 

Would like bring back the auto-save function in 3.x Editor in some form - it could be just like 3.x, or just auto save changes when user begins operate on attachments.