Support default content entities

This is a Roadmap ToDo Issue for Phase 1. Besides updating the Issue Summary, are there some child issues that should be created for this issue?
I am taking a first pass at some minor updates to the summary.

Reviewing a related docs https://git.drupalcode.org/project/distributions_recipes/-/blob/1.0.x/do..., I am creating an issue to remove "Deploying the content created by a Drupal recipe is out-of-scope." which conflicts with the project Roadmap.

Related:

• 🌱 [meta] Deploying configuration that depends on content Active (hah, already listed by @nedjo a year ago! 👍)
• 🐛 BlockManager is too eager in providing fallback to "Broken" block: it obscures genuine problems Active

It still smells like experimental default content module in core so it's related in its queue 📌 Add handling of ConfigEvent::IMPORT_MISSING_CONTENT Needs review

Primary blocker is found and fixed 🐛 Add ConfigImporter to \Drupal\Core\Config\Importer\MissingContentEvent Fixed