Option to skip adding default body fields

Problem/Motivation

Right now, Drupal core adds a default body field to newly created node and block_content types. As a site builder, I want to be able to skip this.

Proposed resolution

Check whether site settings does have an omit_adding_default_body key set to TRUE, and if it does, do not add the default body fields.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet