create abstract method
Creates a symbolic link. Returns a `Future<Link>` that completes with
the link when it has been created. If the link exists,
the future will complete with an error.
If recursive is false, the default, the link is created
only if all directories in its path exist.
If recursive is true, all non-existing path
components are created. The directories in the path of target are
not affected, unless they are also in path.
On the Windows platform, this will only work with directories, and the target directory must exist. The link will be created as a Junction.
Only absolute links will be created, and relative paths to the target will be converted to absolute paths by joining them with the path of the directory the link is contained in.
On other platforms, the posix symlink() call is used to make a symbolic
link containing the string target. If target is a relative path,
it will be interpreted relative to the directory containing the link.
Implementation
Future<Link> create(String target, {bool recursive = false});