message: nydus-image/inspect: also print a sign telling file types
  l presents for symlink
  presents for regular file
  d presetns for directory
diff: @@ -232,8 +232,19 @@ impl RafsInspector {
  self.iter_dir(|f, inode, _idx, _offset| {
  trace!("inode {:?}, name: {:?}", inode, f);
  + let sign = if inode.is_reg() {
  + "-"
  + } else if inode.is_dir() {
  + "d"
  + } else if inode.is_symlink() {
  + "l"
  + } else {
  + " "
  + };
  +
  println!(
  - r#" {inode_number} {name:?}"#,
  + r#"{} {inode_number:<8} {name:?}"#,
  + sign,
  name = f,
  inode_number = inode.i_ino,
  );
  