Support COMMENT and ATTRIBUTE for CREATE USER

[mjonss]

Feature Request

Is your feature request related to a problem? Please describe:

MySQL supports both COMMENT as well as ATTRIBUTE (json_object) for additional metadata per user account (like who created it, why does it exist etc.)

Describe the feature you'd like:
Add support for COMMENT 'free text comment' and ATTRIBUTE 'json_object' in:
CREATE USER [COMMENT '' | ATTRIBUTE '<json_object>']

Describe alternatives you've considered:
n/a, missing compatible feature with MySQL

Teachability, Documentation, Adoption, Migration Strategy:

When managing a lot of accounts, it is hard to understand why a specific account is for and if it really is needed, and by whom it was created and when.

[Tangruilin]

If I'd like to fix it, what can I read as ref

[dveeden]

Looks like this was done in #38201 / #38172

mysql> CREATE USER 'foo'@'%' COMMENT 'test';
Query OK, 0 rows affected (0.05 sec)

mysql> CREATE USER 'bar'@'%' ATTRIBUTE '{"reference": "https://example.com/tickets/000001"}';
Query OK, 0 rows affected (0.04 sec)

mysql> SHOW CREATE USER 'foo'@'%'\G
*************************** 1. row ***************************
CREATE USER for foo@%: CREATE USER 'foo'@'%' IDENTIFIED WITH 'mysql_native_password' AS '' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK PASSWORD HISTORY DEFAULT PASSWORD REUSE INTERVAL DEFAULT ATTRIBUTE '{"comment": "test"}'
1 row in set (0.01 sec)

mysql> SHOW CREATE USER 'bar'@'%'\G
*************************** 1. row ***************************
CREATE USER for bar@%: CREATE USER 'bar'@'%' IDENTIFIED WITH 'mysql_native_password' AS '' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK PASSWORD HISTORY DEFAULT PASSWORD REUSE INTERVAL DEFAULT ATTRIBUTE '{"reference": "https://example.com/tickets/000001"}'
1 row in set (0.01 sec)

mysql> SELECT TIDB_VERSION()\G
*************************** 1. row ***************************
TIDB_VERSION(): Release Version: v7.2.0
Edition: Community
Git Commit Hash: 9fd5f4a8e4f273a60fbe7d3848f85a1be8f0600b
Git Branch: heads/refs/tags/v7.2.0
UTC Build Time: 2023-06-27 15:04:42
GoVersion: go1.20.5
Race Enabled: false
Check Table Before Drop: false
Store: tikv
1 row in set (0.00 sec)