Due to the deletion of dependent objects (issues etc), project deletion may take a long time.
This patch moves the actual project deletion into an ActiveJob job. It also introduces a new project status (SCHEDULED_FOR_DELETION) that is used to effectively hide the project that is about to be deleted (and any potential descendant projects) from the system immediately.
A security notification is sent out to the user that deleted the project, informing about success / failure.
The projects list is extended to be able to filter for the new status, so in case of a failure, the project can still be accessed for examination.
Patch by Jens Krämer.
git-svn-id: https://svn.redmine.org/redmine/trunk@21591 e93f8b46-1217-0410-a6f0-8f06a7374b81
