cpp/experimental/fs/create directory

@1@ Creates the directory as if by POSIX mkdir with a second argument of  (the parent directory must already exist). If already exists and is already a directory, the function does nothing (this condition is not treated as an error). @2@ Same as, except that the attributes of the new directory are copied from (which must be a directory that exists). It is OS-dependent which attributes are copied: on POSIX systems, the attributes are copied as if by On Windows OS, the attributes are copied as if by

@3@ Executes for every element of  that does not already exist.

The non-throwing overloads return if any error occurs.

Return value
@1,2@ if directory creation is successful,  otherwise.

Exceptions
@1,3@ @2@