Update DynamicEntityReferenceItem according to EntityReferenceItem

#2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities is also making changes in EntityReferenceItem

Added my changes based on #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities.

No it will be green once #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities is in.

Also related #2363099: Using translated field definition descriptions in entity schema results in different schema definitions, resulting in update.php changes

More related issues #2386559: ERItem::setValue(array('entity' => $entity) produces broken Items and #2137309: Typed data does not handle set() and onChange() consistently

#2137309: Typed data does not handle set() and onChange() consistently is in and it has broken HEAD and I have no idea how to fix this. Here is some more work. DynamicEntityReference is now exactly same as EntityReference :/

+++ b/src/Plugin/Field/FieldType/DynamicEntityReferenceItem.php
@@ -70,10 +70,8 @@ class DynamicEntityReferenceItem extends ConfigurableEntityReferenceItem {
-    $properties['target_id'] = DataDefinition::create('integer')
-        ->setLabel(t('Entity ID'))
-        ->setSetting('unsigned', TRUE)
-        ->setRequired(TRUE);

This change is due to #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities. We are only using content entities unlike ER so our taget_id will always be integer. If and when we plan to support config entities then we can update it to support strings.

I have seen the error in #13 and thanks for the idea I'll try to investigate more.

I am doing setRequired(TRUE) because of #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities. Is there a reason why we want to keep it a string? We are only supporting entities which are implementing FieldableEntityInterface so making it integer make sense to me unless you have some other reason.
DER field can only support either content entities or config entities per field. In the future we can add a field storage option to choose between content entities or config entities and then we can update DERI::propertyDefinitions() and DERI::schema() same as ERI::propertyDefinitions() and ERI::schema() to support both content entities and config entities.

Fixes after #2386559: ERItem::setValue(array('entity' => $entity) produces broken Items and #1963340: Change field UI so that adding a field is a separate task haven't fixed #13. This patch is rerolled over #2232477-134: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities

I have added individual commits for all the above fixed issues so that we can deal with the problem in hand here is the reroll version of the patch.

Bot is back. This should be green.

Postponing it on #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities

Fixed the fails, updated the patch according to #2232477: Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities committed version, have done some clean up and added some docs so that we'll get less confuse next time ;-).

1. +++ b/src/Plugin/Field/FieldType/DynamicEntityReferenceItem.php
   @@ -80,30 +87,18 @@ class DynamicEntityReferenceItem extends ConfigurableEntityReferenceItem {
   -      // $properties['entity']->getTargetDefinition()->addConstraint('Bundle', $settings['target_bundle']);
   

   We can add this constraint in setValue(). Do you think it is worth it? If yes we can discuss this in follow up.

Fixed on commit. Thanks for the review and support.

Added #2405467: Add EntityType and Bundle constraint on entity property of DynamicEntityReferenceItem for #28