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

Rearrange the different settings in the same place with a segment view
for all resources. Implement a new flag for resources "bookable" which
indicates the entries with a booking methods. Guests users doesn't have
a right to view courses with booking methods.