Move wstring to string conversion to StringUtils.cpp and update most HID get serial number functions to use it

Controllers/HyperXKeyboardController/HyperXAlloyFPSController/HyperXAlloyFPSController.cpp

@@ -11,6 +11,7 @@
 
 #include <cstring>
 #include "HyperXAlloyFPSController.h"
+#include "StringUtils.h"
 
 using namespace std::chrono_literals;
 
@@ -50,10 +51,7 @@ std::string HyperXAlloyFPSController::GetSerialString()
         return("");
     }
 
-    std::wstring return_wstring = serial_string;
-    std::string return_string(return_wstring.begin(), return_wstring.end());
-
-    return(return_string);
+    return(StringUtils::wstring_to_string(serial_string));
 }
 
 void HyperXAlloyFPSController::SetLEDsDirect(std::vector<RGBColor> colors)