[php-src] Issue #12414: Expose pdo_parse_params to userspace

Issue: https://github.com/php/php-src/issues/12414 Author: chx ### Description Drupal has been using PDO for a long time now but as it doesn't have async support, the project is adding a mysqli driver. A sticky point here is the lack of support for named placeholders which are widely used in Drupal land but mysqli doesn't support them. Currently the project is considering parsing the SQL string in userspace to convert the named placeholders to positional ones. This does seem like a waste because PDO already contains battle tested, performant code to do this: pdo_parse_params. Exposing this to userspace would solve the problem. What do you think? If the maintainers of the project agree to the idea I can take a stab at coding this.