Support CLIENT_OPTIONAL_RESULTSET_METADATA

[ybbct]

Issue description

This option will improve performance in many scenarios
https://dev.mysql.com/worklog/task/?id=8134

https://www.facebook.com/weixiang.zhai/posts/678596755543802

[julienschmidt]

The flag is not documented here: https://dev.mysql.com/doc/internals/en/capability-flags.html

According to the "Low Level Design" part of the worklog, the following is used:

#define CLIENT_OPTIONAL_RESULTSET_METADATA (1UL << 25)

Further source: https://dev.mysql.com/doc/refman/8.0/en/c-api-optional-metadata.html

[Bisstocuz]

The flag is not documented here: https://dev.mysql.com/doc/internals/en/capability-flags.html

According to the "Low Level Design" part of the worklog, the following is used:

#define CLIENT_OPTIONAL_RESULTSET_METADATA (1UL << 25)

Further source: https://dev.mysql.com/doc/refman/8.0/en/c-api-optional-metadata.html

It's right, this option will improve performance in many scenarios with up to 180% QPS performance improvement.
https://dev.mysql.com/doc/c-api/8.0/en/c-api-optional-metadata.html

Is it possible for github.com/go-sql-driver/mysql to support this feature?