new function: ::content::revision::export_to_filesystem
This change moves functionality from file-storage to acs-content-repository. all application packages should be free of internals, such as the storage type. Storage_type should be handeled in the content-repository package.
We are not yet done, there is still more to do in this respect in the file-storage package.
The refactored code is a first step to become able to provide plugins for backends for storing content in different systems. Instead of using switch statements to distinguish between backends "file", "lob" and "text", procs with a suffix of the storage name are provided now. Essentially, by providing process with additional suffixes can be used to provide additional storage systems.
In addition, the deletion handling was also refactored such that the non-scalable functions iterating over all items (such as "cr_check_orphaned_files") will become obsolete. This is imporant for content repositories with double and triple digit terabytes.