Support file uploads and the device details page for Elegoo Centauri Carbon 2 (#13212)

* Support file uploads and the device details page for CC2 printers.

* Resolved build issues for Linux and macOS.

* 1. Added `ElegooPrinterWebViewHandler` to handle WebUI messages for Elegoo printers. Other printers will keep the current behavior.
2. Added a static `get_print_host_webui` method in `PrintHost` to retrieve the printer WebUI URL.

* Improved timeout handling for CC2 file upload and SN info APIs.

---------

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/slic3r/GUI/PrinterWebViewHandler.hpp

@@ -0,0 +1,36 @@
+#ifndef slic3r_PrinterWebViewHandler_hpp_
+#define slic3r_PrinterWebViewHandler_hpp_
+
+#include <memory>
+#include <wx/webview.h>
+#include <wx/string.h>
+
+class wxWebView;
+
+namespace Slic3r {
+namespace GUI {
+
+class PrinterWebView;
+
+class PrinterWebViewHandler {
+public:
+    explicit PrinterWebViewHandler(PrinterWebView& owner);
+    virtual ~PrinterWebViewHandler();
+
+    virtual void on_loaded(wxWebViewEvent &evt);
+    virtual void on_script_message(wxWebViewEvent &evt);
+
+protected:
+    PrinterWebView& owner() const;
+    wxWebView*      browser() const;
+
+private:
+    PrinterWebView& m_owner;
+};
+
+std::unique_ptr<PrinterWebViewHandler> create_printer_webview_handler(PrinterWebView& owner);
+
+} // GUI
+} // Slic3r
+
+#endif /* slic3r_PrinterWebViewHandler_hpp_ */