Remove explicit references to Layout Builder

Problem/Motivation

As a follow-up of #3593247: Move some entity view logic to buildable plugins and an alternative to #3545596: Move Layout builder support to external module, can we to totally remove any explicit reference of Layout Builder in our code (except migration logic) more precisely:

• the EntityViewDisplay VS LayoutBuilderEntityViewDisplay split
• and hopefully the EntityViewDisplayForm VS LayoutBuilderEntityViewDisplayForm split

We are currently keeping those 2 classes with explicit reference to Layout Builder because of the classes we are extending from Core:

• LayoutBuilderEntityViewDisplay is extending Drupal\layout_builder\Entity\LayoutBuilderEntityViewDisplay instead of Drupal\Core\Entity\Entity\EntityViewDisplay
• LayoutBuilderEntityViewDisplayForm is extending Drupal\layout_builder\Form\LayoutBuilderEntityViewDisplayForm instead of Drupal\field_ui\Form\EntityViewDisplayEditForm

Proposed resolution

Can we promote composition over inheritance?

• EntityViewDisplay has already no logic of its own, just an empty shell for the EntityViewDisplayTrait
• LayoutBuilderEntityViewDisplay is only implementing EntityInterface::preSave() which could be replaced by hook_entity_presave with conditions
• EntityViewDisplayTrait is implementing/overriding:
  • EntityInterface::postSave() could be replaced by hook_entity_update as we already do for display_builder_views?
  • EntityInterface::delete() could be replaced by hook_entity_delete?
  • ConfigEntityInterface::calculateDependencies() and ConfigEntityInterface::onDependencyRemoval() may be addressable with #3540069: Evaluate ObjectWithPluginCollectionInterface
  • EntityViewDisplayInterface::buildMultiple() could be replaced by hook_entity_view or hook_entity_display_build_alter ?
  • DisplayBuilderEntityDisplayInterface::isDisplayBuilderEnabled() could be moved to EntityView buildable plugin
  • Other DisplayBuilderEntityDisplayInterface methods could be moved to move to EntityViewOverride buildable plugin

We can group all hook implementations which is altering Entity View Display entity type into a single class which will look very similar to the current EntityViewDisplayTrait. Like an "entity type decorator"

For forms:

• EntityViewDisplayForm has already no logic of its own, just an empty shell for the EntityViewDisplayFormTrait
• DisplayBuildablePluginManager has just a little form alteration, which could be replaced by entiity_form_alter hook.
• EntityViewDisplayFormTrait only overrides FormInterface::submitForm()