Provide example content blocks as usable bundle

[typecat]

As an integrator, I want to use the example content blocks in my installation, to benefit from existing solutions.

Acceptance criteria

• The example content blocks are provided as real-life
• The example content blocks are provided as a composer bundle, instead as build packages in this repository
• The example bundle can be installed in a real-life project

Remarks on content

If the examples also have proper frontend and backend styles, thus being close to real-life cases, integrators could even uses them in their projects.
A nice side effect would be the promotion of TYPO3's Asset Collector.

[jonaseberle]

See https://github.com/TYPO3-Initiatives/content-block-registration-api#via-composer for one working example.

Or https://packagist.org/search.html?type=typo3-cms-contentblock to get a list.