Rel v6r11 new data manager

- New DataManager class to replace the ReplicaManager
- replace the calls to ReplicaManager with calls to DataManager/FileCatalog/StorageElement
- Reshape a little bit the StorageElement to prepare the change from PFN to LFN
- add getLfnForPfn into StorageElement, and make se.getPfnForLfn and se.getPfnForProtocol compliant with the Successful/Failed return type convention
- remove the use of class method for the dataManager and fileCatalog with instance attributes
- add accounting for DataManager.getFile and account for the file size for removal operations  (https://github.com/DIRACGrid/DIRAC/issues/1331)