Move the functions of OlatRootFile and OlatRootFolder to the Local
implementations to simplify the use of VFS, implements factory methods
in VFSManager, reduce the number of call to meta informations in folder
listing

Fix deletion of metadata, fix left files by restore of versioned files,
implement restore of metadata of deleted versioned files, implements an
upgrader to delete metadata of deleted resources, courses, groups,
forums, users and temporary uploaded files

OO-3532, OO-3532: add a third queue especially for deletion and export of users to not disturb the other services, export participant folder's drop box of users

OO-3489, OO-3490, OO-3491, OO-3495, OO-3499, OO-3500, OO-3501: finish the export process, delete files after zipping, send email... and more exported data

OO-3489, OO-3492, OO-3493, OO-3494, OO-3496, OO-3497: infrastructure to export user data, export  portraits, notes, personal folder, calendars, subscriptions, delete calendars after usser deletion