Various methods of \Drupal\Core\Database\StatementInterface have changed their signature for PHP 8

Problem/Motivation

Under PHP 8 installing Drupal results in errors because \Drupal\Core\Database\StatementInterface::fetch() does not match \PDOStatement::fetch()

Proposed resolution

It seems that we can add the necessary scalar typehints and it works on both PHP 8 and PHP 7.3 and up. I wonder if it works oon Drupal 8 and PHP 7.0.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet