Refactoring on `utils.cc' and adjacents

Completely removed the `utils.cc' by moving residual functions into
sub-classes of `utils/'

src/request_body_processor/multipart.cc

@@ -28,11 +28,12 @@
 
 #include "modsecurity/collection/collections.h"
 #include "modsecurity/rules.h"
-#include "src/utils.h"
 #include "utils/msc_string.h"
 
+
 using modsecurity::utils::String;
 
+
 namespace modsecurity {
 namespace RequestBodyProcessor {