Entity Browser form trait does not work with children

Problem/Motivation

When using entity browser form trait with an image that is on a subform of a parent form, the image is not able to be selected correctly within the processEntityBrowserSelected function. This is due to the parent array not encapsulating the entire path through subforms.

Steps to reproduce

Add a form with an entity browser form trait as a sub-form to the parent form. When selecting an image, it will go through with the selected image but the entity will not be found.

Proposed resolution

Change the parent array to not use magic numbers and instead use the correct pathing.

Remaining tasks

Review patch