ImageItem::defaultStorageSettings() should override display_default

Problem/Motivation

The value is always set to TRUE in \Drupal\file\Plugin\Field\FieldWidget\FileWidget::process (line 411) and causes invalid values from FormState::getValues after calling FormBuilder::buildForm if the form isn't submitted

Steps to reproduce

Create an entity form with an image widget
Call buildForm on the form builder for that form and inspect $form_state->getValue(['your_field_name', 0, 'display']) and note it will be FALSE despite the value being hard-coded to 1 in \Drupal\file\Plugin\Field\FieldWidget\FileWidget::process

Proposed resolution

Override ::defaultStorageSettings for ImageItem and set display_default to TRUE (hence overriding FileItem::defaultStorageSettings()' default of FALSE).

Remaining tasks

None.

User interface changes

None.

Introduced terminology

None.

API changes

None.

Data model changes

None.

Release notes snippet

N/A