Issue #2100329 by cosmicdreams: Use \Drupal instead of Drupal to make IDEs and static code analyse tools happy.

Revert "Issue #2060405 by Wim Leers: Fixed Impossible to uninstall any module using the file usage service, because it is impossible to delete all file usages by a module."

This reverts commit 858674f0.

Issue #1847002 by tim.plunkett, effulgentsia, msonnabaum: Move entity type classes from Drupal$provider\Plugin\Core\Entity to Drupal$provider\Entity.

Issue #2060405 by Wim Leers: Fixed Impossible to uninstall any module using the file usage service, because it is impossible to delete all file usages by a module.

This reverts commit a567be3e.

Issue #1763974 by tim.plunkett, EclipseGC, berdir, xjm, neclimdul, FabianX: Convert entity type info into plugins.