Consider deprecating old validation API

**Feature request**
It would be great to have logging for parsers.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_logging` with default `false`.

The issue does not identify files or tests. Start by locating the parser entry points and existing configuration handling, then determine where logging would be emitted and how configuration defaults are tested. Done means parser logging is controlled by enable_logging, which defaults to false.

Written by the indexing model from the issue text.