Confine config import to the preset directory (#15608)

import_presets reduced each zip entry to a basename by stripping only
'/', so on Windows an entry named with '\' separators kept its
directory components and was extracted wherever they pointed. Strip
both separators, and reject any entry whose name still escapes the
extraction folder.

The preset name from the JSON and the bundle id from
bundle_structure.json were joined onto the preset directory unchecked
as well, which let either of them write outside it on every platform.
Both are now validated before anything is written.

The check is the is_path_within_root helper the 3MF importer already
had, moved to Utils so both importers share it. It treats '/' and '\'
as separators on every platform, so a bundle that would escape on one
OS is rejected on all of them.

src/libslic3r/Utils.hpp

@@ -255,6 +255,10 @@ extern bool is_gallery_file(const std::string& path, char const* type);
 extern bool is_shapes_dir(const std::string& dir);
 //BBS: add json support
 extern bool is_json_file(const std::string& path);
+// True if rel_path is relative, has no ".." component and, joined to root, still resolves inside it.
+// Both '/' and '\\' are treated as separators on every platform, so an archive rejected on one OS
+// is rejected on all of them.
+extern bool is_path_within_root(const std::string &rel_path, const boost::filesystem::path &root);
 
 // Orca: custom protocal support utils
 inline bool is_orca_open(const std::string& url) { return boost::starts_with(url, "orcaslicer://open"); }