Add wxFileType::GetExpandedCommand()

This new method allows to get the command expanded with the given file name
for commands other than "Open" and "Print".

Closes #17367.

include/wx/mimetype.h

@@ -353,6 +353,9 @@ public:
     // dtor (not virtual, shouldn't be derived from)
     ~wxFileType();
 
+    wxString
+    GetExpandedCommand(const wxString& verb,
+                       const wxFileType::MessageParameters& params) const;
 private:
     // default ctor is private because the user code never creates us
     wxFileType();