[RFC] Plan for MongoDB ODM v3 (new major release)

[GromNaN]

MongoDB ODM v2 was released in 2018 and PHP and MongoDB have come a long way since then.

I'd like to propose a plan for things that involve breaking changes and that can be achieved for a 3.0 release. The goal is to make the version 2.last version 100% compatible with 3.0, as soon as all deprecations are resolved (following the same process as Symfony of deprecating before removing).

• Drop lazy proxy libraries and use native lazy objects
  • Add support for native lazy objects in v2.x
  • Require PHP 8.4+
• Rename lib/Doctrine/ODM/MongoDB/ to src/
• Drop support for annotations. They are replaced by PHP Attributes
• Add native types to all properties
• Add native return types
• Add native parameter types (this is backwards compatible, should be already the case)
• Make soft-final classes, hard-final
• Require ext-mongodb 2
• Remove support for CollectionInfoIterator, CollectionInfoCommandIterator, IndexInfoIterator, IndexInfoIteratorIterator from ext-mongodb 1.x
• Remove inheritance strategies COLLECTION_PER_CLASS Deprecate COLLECTION_PER_CLASS inheritance #2742
• Make classMetadata fields public readonly
• Switching "symfony/var-dumper" in require-dev #2448
• Require composer-runtime-api: ^2.0 [3.x] Require Composer v2 #2782 (see PHPLIB-1302: Use Composer\InstalledVersions mongodb/mongo-php-library#1262)
• Use #[AsCommand] attribute to enable lazy-loading