Local file exposure via prefix path check

Path traversal in CefSharp before 148.0.90 allows remote attackers to read local files via crafted URLs handled by FolderSchemeHandlerFactory. In FolderSchemeHandlerFactory.cs, the handler decoded and canonicalized the request path, then trusted filePath.StartsWith(rootFolder, StringComparison.OrdinalIgnoreCase) to keep access under the configured root, which let sibling directories such as www2 pass when their paths shared the same prefix. Reachability requires an application to register FolderSchemeHandlerFactory for a custom scheme or HTTP or HTTPS and for an attacker to cause the embedded browser to request the crafted URL.