[Tracking issue] Add json datatype

[CookiePieWw]

What type of enhancement is this?

Other

What does the enhancement do?

Support to store and query json data as an independent datatype.

Tasks

• Build a benchmark to choose the representation of json inside memory and SST files.
  • see https://github.com/CookiePieWw/json-format-in-parquet-benchmark for more information.
• RFC docs: json datatype rfc #4515
• Add json datatype and other related support.
  • feat: add json data type #4619
  • Currently the insertions of json type through "PREPARE" and "EXECUTE" stmt are not available.
• Add UDFs for querying json.
  • Add casts between jsonb value and other types, e.g. parse_jsonb("{\"a\": \"b\"}")
    • string to json: see to_json in feat: add json data type #4619
  • Add functions to query inside json through paths, e.g. get_by_path_int(".a.b", json)
    feat: add respective get_by_path UDFs for JSON type #4720
  • Add functions to check if the given json is of specified json type.
    feat: add respective json_is UDFs for JSON type #4726

[WenyXu]

Future work will be tracked in issue #4805.