FileNotebookManager: Use shutil.move() instead of os.rename()

`os.rename()` fails in case the new path is on a different
filesystem. For example if a file in `/tmp` is tried to save
to home, it causes following error:

[Errno 18] Invalid cross-device link using os.rename
Merge pull request #5548 from pankajp/notebook-rename-cross-device-link

FileNotebookManager: Use shutil.move() instead of os.rename()