Add tasks
- Added Task and its TaskRun for cleaning cache of a Drupal site.
- Added Task and its TaskRun for database backup of a Drupal site.
- Added Task and its TaskRun for database restore of a Drupal site.
- Added Task and its Taskrun for editing DrupalSite.spec.publish.
Relates to https://gitlab.cern.ch/webservices/webframeworks-planning/-/issues/297