#2498803 Introduce placeholders (#lazy_builder) to replace #post_render_cache

from:
  fqn: 'array_key:#post_render_cache'
to:
  fqn: 'array_key:#lazy_builder'
to:
  fqn: 'array_key:#create_placeholder'
from:
  fqn: 'fn:drupal_render_cache_generate_placeholder'
from:
  fqn: '\Drupal\Core\Render\RendererInterface::generateCachePlaceholder'