feat: Handle duplicate dir names better

If we run `dust /usr/*/Trash`
We see several 'Trash' directories in the output but do not know which
user they belong to.

This fix means if we see duplicate names in a directory we will display
the parent directory name as well

src/display.rs

@@ -273,7 +273,7 @@ fn clean_indentation_string(s: &str) -> String {
     is
 }
 
-fn get_printable_name<P: AsRef<Path>>(dir_name: &P, short_paths: bool) -> String {
+pub fn get_printable_name<P: AsRef<Path>>(dir_name: &P, short_paths: bool) -> String {
     let dir_name = dir_name.as_ref();
     let printable_name = {
         if short_paths {