Make symlinks to directories use a folder icon, or have all symlinks have a symlink icon

### Description

Currently symlinks show the file icon.
It would be nice if symlinks show a directory icon if the target is a directory.
Otherwise, it would be nice if symlinks show the symlink icon.

This is especially important with the short listing format, where a symlink to a directory and a regular file have indistinguishable style (e.g. yellow, with file icon).

- Type of issue :
- [ ] Installation
- [x] Font-related
- [x] Feature request
- [x] Bug in existing feature
- [ ] Developer mode : Code quality / Tests / Documentation

No file or test is named. Start by locating the symlink handling and icon-selection entry points, then inspect how the short listing format renders links. Done means directory symlinks use the folder icon, or all symlinks use a distinct symlink icon, with coverage for the selected behavior.

Written by the indexing model from the issue text.