Add utility for JSON parser to match current field name

[res-life]

closes #1856

JSON parser matches current field name.

Logic of matching field name

• The field name of root { or [ is NULL
• The field name of } or ] is the field name of mached corresponding { or [
• The field name of filed name token is the string of this filed name token
• The direct follow token of filed name token uses the field name of this filed name token

examples:

  
  json = "             {     'k' : [    1  ,  [   1,    2,    3     ] ,     3      ]      }     ";
  // field names:      NULL   k    k    NULL  NULL NULL NULL  NULL  NULL   NULL    k      NULL

  json = "             {    'k1' : {  'k2' : {   'k3': {   'k4':  4    }    }    }     }       ";
  // field names:      NULL  k1    k1  k2    k2   k3   k3   k4    k4   k3   k2   k1   NULL

Signed-off-by: Chong Gao res_life@163.com