Improved query canonicalization

The query does not need to be parsed for it to be canonicalized and the parsing
uses the PCRE2 library. The regular expressions were changed so that only one
call to the function which replaces literal unquoted values is made.

utils/skygw_utils.h

@@ -276,6 +276,7 @@ EXTERN_C_BLOCK_BEGIN
 
 size_t get_decimal_len(size_t s);
 
+char* replace_values(const char* str);
 char* replace_literal(char* haystack, 
                       const char* needle, 
                       const char* replacement);