Add Simple XML Sitemap defaults for Blog content type

Problem/Motivation

The Blog content type is not included in the Simple XML Sitemap by defaults. We should add this. For more information see the parent issue: 📌 Enable at least some entities in Simple XML Sitemap by default Active

Steps to reproduce

Install Drupal CMS with SEO tools recipe + with a Blog recipe
Visit sitemap on /sitemap.xml to see that it is empty (only frontpage is here)
Visit sitemap config on /admin/config/search/simplesitemap/entities to see that nothing is included by default

Proposed resolution

Add the Blog content types (from Content) to be included in the sitemap by default.

Remaining tasks

User interface changes

API changes

Data model changes