Refactoring on `utils.cc' and adjacents

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

src/operators/pm_from_file.cc

@@ -19,9 +19,9 @@
 
 #include "operators/operator.h"
 #include "utils/https_client.h"
-#include "src/utils.h"
 #include "src/utils/msc_system.h"
 
+
 namespace modsecurity {
 namespace operators {
 

src/operators/validate_dtd.cc

@@ -18,7 +18,6 @@
 #include <string>
 
 #include "request_body_processor/xml.h"
-#include "src/utils.h"
 #include "src/utils/msc_system.h"
 #include "operators/operator.h"