Problem/Motivation
The node add page (node_add_list) and the block content add page block_content_add_list are using standalone theme (and template) for theming their page content.
Drupal provides the entity_add_list theme function for this since #2666792: Provide a route provider for add-page of entities is in. This is used by Media module in core.
Proposed resolution
Remove node_add_list and block_content_add_list theme functions and use entity_add_list instead of them.
Remaining tasks
@todo
User interface changes
@todo
API changes
@todo
Data model changes
@todo
Release notes snippet
@todo