Allow printing even if nozzle info isn't reported by firmware. (#12814)

* Don't assume 0.4mm nozzle; format as "unknown" if not defined.

* Skip nozzle diameter and hardness checks if nozzle info unknown.

---------

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

src/slic3r/GUI/GUI_Utils.cpp

@@ -1,6 +1,7 @@
 #include "GUI.hpp"
 #include "GUI_Utils.hpp"
 #include "GUI_App.hpp"
+#include "I18N.hpp"
 
 #include <algorithm>
 #include <boost/lexical_cast.hpp>
@@ -32,6 +33,15 @@ wxDEFINE_EVENT(EVT_VOLUME_ATTACHED, VolumeAttachedEvent);
 wxDEFINE_EVENT(EVT_VOLUME_DETACHED, VolumeDetachedEvent);
 #endif // _WIN32
 
+wxString format_nozzle_diameter(float diameter)
+{
+    if (diameter <= 0.0f) {
+        return _L("Unknown");
+    }
+
+    return wxString::Format("%smm", wxString::FromDouble(diameter));
+}
+
 CopyFileResult copy_file_gui(const std::string &from, const std::string &to, std::string& error_message, const bool with_check)
 {
 #ifdef WIN32