Support remaining JSON functions from MySQL 5.7

[mccxj]

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

scalar function. See https://dev.mysql.com/doc/refman/5.7/en/json-function-reference.html

• JSON_TYPE
• JSON_EXTRACT
• -> equivalent to JSON_EXTRACT()
• ->> equivalent to JSON_UNQUOTE(JSON_EXTRACT())
• JSON_UNQUOTE
• JSON_ARRAY
• JSON_ARRAY_APPEND @erjiaqing expression: add builtin json_array_append #9609
• JSON_ARRAY_INSERT @foreyes expression: add built-in function json_array_insert #11076
• JSON_OBJECT
• JSON_MERGE
• JSON_MERGE_PATCH
• JSON_MERGE_PRESERVE @shinytang6 expression:add support for JSON_MERGE_PRESERVE #8931
• JSON_VALID @kuafou WIP: expression: add builtin function json_valid #7727 @Reminiscent expression: add builtin function json_valid #12596
• JSON_SET
• JSON_INSERT
• JSON_REPLACE
• JSON_REMOVE
• JSON_CONTAINS @mccxj expression: support builtin function json_contains #7443
• JSON_CONTAINS_PATH @xiangyuf expression: support builtin function json_contains_path #7596
• JSON_PRETTY
• JSON_QUOTE @overbool builtin: add json quote #7832
• JSON_SEARCH @pingyu expression/json: add builtin function JSON_SEARCH #8704
• JSON_STORAGE_SIZE
• JSON_DEPTH @pingyu expression: add builtin function JSON_DEPTH #8347
• JSON_KEYS @Kingwl expression: add builtin json_keys #7776
• JSON_LENGTH @Kingwl expression: add builtin function json_length #7739

aggregate function. See https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html

• JSON_ARRAYAGG @Kingwl expression: add json_arrayagg and json_objectagg #7824
• JSON_OBJECTAGG @Kingwl expression: add json_arrayagg and json_objectagg #7824

[xiangyuf]

I will implement JSON_CONTAINS_PATH

[zz-jason]

/cc @hicqu @XuHuaiyu

[zz-jason]

@mccxj The aggregate functions list here are duplicated with #7623

[morgo]

For JSON_MERGE_PRESERVE: JSON_MERGE should be renamed to this, and JSON_MERGE can become an alias to JSON_MERGE_PRESERVE.

[morgo]

I am working on updating the JSON documentation in pingcap/docs#656

[morgo]

@erjiaqing thank you for working on json_array_append! Are you interested on working on json_array_insert ? 😄 😄

[wwar]

JSON_STORAGE_SIZE can be checked off as complete. I have manually verified it works.

[ghost]

I am going to close this issue in favor of #14486

There is duplication between these issues, and 14486 is a better representation of what issues are outstanding.