Add json_normalize function to json_lib

This patch implements a library for normalizing json documents.
The algorithm is:
* Recursively sort json keys according to utf8mb4_bin collation.
* Normalize numbers to be of the form [-]<digit>.<frac>E<exponent>
* All unneeded whitespace and line endings are removed.
* Arrays are not sorted.

Co-authored-by: Vicențiu Ciorbaru <vicentiu@mariadb.org>

include/json_lib.h

@@ -1,6 +1,8 @@
 #ifndef JSON_LIB_INCLUDED
 #define JSON_LIB_INCLUDED
 
+#include <my_sys.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -431,6 +433,9 @@ int json_locate_key(const char *js, const char *js_end,
                     const char **key_start, const char **key_end,
                     int *comma_pos);
 
+int json_normalize(DYNAMIC_STRING *result,
+                   const char *s, size_t size, CHARSET_INFO *cs);
+
 #ifdef  __cplusplus
 }
 #endif