* fix: absolutize path against its parent if it was a symlink.
On Linux this happens because Rust calls readlink but doesn't canonicalize the resultant path.
* feat: playground function to create symlinks
* fix: use playground dirs
* feat: test for #1631, shift tests names
* Creation of FilesystemShell with custom location may fail
* Replace ichwh with which
* Creation of FilesystemShell with custom location may fail
* Replace ichwh with which
* fix: add ichwh again since it cannot be completely replaced
* fix: replace one more use of which