Support for Drupal 12

Problem/Motivation

Drupal 12 can now be tested on Gitlab CI with the PHPUNIT next major job.

Add Drupal API and PHP compatibility changes to support Drupal 12.

Steps to reproduce

Proposed resolution

In the same development branch 1.x, as compatibility for older core versions should stay the same: 11.3 min.

Among some of the expected changes:

• Move all .module file's hooks to a Hook class with PHP attributes
• Add types to all function signatures and declare strict types
• Any PHP compatibility changes
• Any other changes

Acceptance tests

• All the tests and jobs should pass 🟢 for Drupal 12 (next major).
• Composer dependency should resolve correctly for Drupal 12.

Remaining tasks

User interface changes

API changes

Data model changes