Show affected_rows in `information_schema.processlist`

[ekexium]

Feature Request

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

Describe the feature you'd like:

Show affected_rows in information_schema.processlist

Describe alternatives you've considered:

• Special syntax
• Logs. It is already in expensive_logs.

Teachability, Documentation, Adoption, Migration Strategy:

For long-running statements, especially pipelined DML(@@tidb_dml_type=bulk), we need a straightforward way to know the progress.