Bug fixes

Thanks to debdatta.sarkar we could make progress with the UI. Some admin links were visible, although users did not have permission.

Fixing minor bug where use statement was listed twice in module file for HTML... many apologies.

All the awesomeness from 8.x-1.8.

- #3123046: Drupal 9 Readiness
- #3123049: \Drupal calls should be avoided in classes, use dependency injection instead - Include config filter as an optional dependency - usage of setter injection pattern.

Changes since 8.x-1.7: