Add support for custom JSON path in LLD macros

Work breakdown form ZBXNEXT-4087:  

• LLD will accept normal JSON containing an array, i.e. without 'data' object
  1. Zabbix will automatically extract macro and value if an array field uses {#MACRO} syntax as a key
  2. For backward compatibility Zabbix will accept JSON notation with "data" element.
     1. If JSON contains object with only one "data" array element, then it will automatically extract content of the element using JSON Path $.data
• LLD will accept optional user-defined list of LLD macros
  1. LLD rule configuration form will be extended to support a new tab to configure LLD macros
  2. A set of {#MACRO}=<json path> can be defined, for example: {#NAME}=$.name, {#FS}=$.fs.name, {#MOUNT}=$.fs.mountpoint
     1. JSON keys with any special characters and unicode must be supported using optional square bracket notation, like $'unicode + special chars #1''unicode + special chars #2'
  3. User defined LLD macros will override macros found in JSON (in reality it should not happen)
  4. Supported syntax for JSON path must be documented
• The "data" element will be removed from all items related to discovery (agent, jmx, snmp, odbc, etc)

1. 1. Any new native discovery checks will use new syntax without the "data" elements