Optimize adaptation of document backed file system items

Currently when adapting a document as a FileSystemItem, to compute its path we recurse on the document's ancestors and adapt each of them as a FileSystemItem which is:

• costly
• complex to debug

A first optimization would be, when the id of the parent FileSystemItem is known, to pass the actual parent FileSystemItem instead of its id only to the constructor responsible for adapting the doc.
See:

protected AbstractDocumentBackedFileSystemItem(String factoryName,
            DocumentModel doc) throws ClientException

and

protected AbstractDocumentBackedFileSystemItem(String factoryName,
            String parentId, DocumentModel doc) throws ClientException