Drupal core's Place Block module deprecated

The experimental core module Place Block has been deprecated as it will be superseded by another module Layout Builder (available since Drupal 8.7.0). The Place Block module will be removed in Drupal 9.

Alternative solutions:

• If the blocks specifically need to be placed in a theme region this project is the recommended contrib replacement Layout Builder Everywhere, which is being developed for eventual inclusion with the Drupal core Layout Builder module.
• The Place Block is also available as a contributed module for sites that need an immediate upgrade path for Drupal 9.
• If a Composer-managed site that has a custom module that somehow has a constraint on a specific version of block_place you need to update the dependency version to match https://www.drupal.org/project/block_place versions.

The change introduces also a trait Drupal\Tests\DeprecatedModulesTestTrait which can be used to filter out deprecated modules for the modules list (array).