Directory Tree Copy Fix: Automatic Directory Creation on STOR

Barring exceptions, when `STOR` is used on a working path that does not yet exist, that path should be created.  This branch also adds a "directory-exists" code (a candidate I think for `include/services/fs.h` in `libctru`) for changing behavior slightly for a directory that already exists; this should help with adding error management.

The reason for this small patch is to fix copying over directory trees when using clients that use this mechanism.