Split DisplayBuilder logic into a view_builder handler

Problem/Motivation

DisplayBuilder class is massive (660 lines including 380 PHP lines).

Some entity types have a view_builder handler to move the rendering logic into a dedicated class. Example:

  handlers: [
    'storage' => NodeStorage::class,
    'view_builder' => NodeViewBuilder::class,
    'access' => NodeAccessControlHandler::class,

Proposed resolution

Let's do the same.