before this patch we allow a rename in the following cases:
- the user has rename permission on both source and target path
- the user has delete permission on source path and create/upload on
target path
we now check only the rename/rename_files/rename_dirs permissions.
This is what SFTPGo users expect.
This is a backward incompatible change and it will not backported to
the 2.2.x branch
Signed-off-by: Nicola Murino <nicola.murino@gmail.com>