[CH] Use get_json_object instead of from_json

[lgbo-ustc]

Description

We find some user will first tranform a json string into a map or other structure, and then access one field of the strcuture, as following

from_json(json_str, 'map<string,string>')['live_type']

We may could use get_json_object to replace this query.

[lgbo-ustc]

We compare the two methods as following

select count(x) from (select from_json(s, 'Map<String, String>')['key2'] as x from test_map_json);

select count(x) from (select get_json_object(s, '$.key2') as x from test_map_json);