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

Controllers/SRGBmodsController/SRGBmodsLEDControllerV1/SRGBmodsLEDControllerV1.cpp

@@ -11,6 +11,7 @@
 
 #include <cstring>
 #include "SRGBmodsLEDControllerV1.h"
+#include "StringUtils.h"
 
 using namespace std::chrono_literals;
 
@@ -40,10 +41,7 @@ std::string SRGBmodsLEDControllerV1::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 SRGBmodsLEDControllerV1::SetChannelLEDs(unsigned char /*channel*/, RGBColor* colors, unsigned int num_colors)