Support for query attributes

[jainsneha2305]

Please add support for query attributes

https://dev.mysql.com/doc/refman/9.6/en/query-attributes.html

[sidorares]

Wire format:
COM_QUERY: https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_query.html
COM_STMT_EXECUTE: https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_stmt_execute.html

open questions:

• map vs array? While semantically it's a map, over the wire values sent as a list of key-value pairs. Map won't allow to specify order or send duplicate keys ( leaning towards map as better DX )
• attributes are serialized in a similar way to prepared statements parameters. Currently we infer PS parameter type from JS type ( null, number, string, date, buffer ) and there is no user control over it. This might change in the future, see Change the way types for prepared statement parameters are calculated #1407 (comment) . Might worth discussing if we want that change first to avoid backwards incompatible releases

[sidorares]

@jainsneha2305 published as v3.21.0
https://sidorares.github.io/node-mysql2/docs/documentation/query-attributes ( history section is currently incorrect, I'll publish documentation fix some time later )

[jainsneha2305]

Thanks @sidorares for quick addition of this feature.