chmod -R -L: the path is lost for a dangling symlink below the operand #16152

With -R -L, a dangling symlink inside the tree is reported without its name:

$ mkdir d; ln -s missing d/dang
$ chmod -R -L 755 d

GNU (9.10):

chmod: cannot operate on dangling symlink 'd/dang'

uutils (main):

chmod: No such file or directory

With -v, GNU also prints 'd/dang' could not be accessed after the error; uutils prints nothing.

In safe_traverse_dir (src/uu/chmod/src/chmod.rs), when metadata_at fails, only the PermissionDenied case gets the entry path; other errors go through err.into() without it.

For a dangling symlink given as the operand itself, chmod already prints the GNU error; its -v line is covered by #15883.

Found by @fixfon while reviewing #15935.