3a75f10af1
This now uses `node_to_string` for both missing and seen Ids, which includes the snippet of code for which the Id was allocated. Also removes the duplicated printing of `HirId`, as `node_to_string` includes that already. Similarly, changes all other users of `node_to_string` that do so, and changes the output of `node_to_string`, which is now "$hirid ($what `$span` in $path)".