Add compatibility with Symfony 6

[franmomu]

There are many BC breaks here

• DoctrineMongoDBExtension: I think they could be acceptable since I think it's quite unusual that someone extends from it.
• DoctrineMongoDBBundle: The same thing, I think it is unlikely that someone extends it.
• MongoDBQueryBuilderLoader and DocumentType: I'm not sure about these ones, should we comment on [META] Symfony 6 return type declarations symfony/symfony#43021? or do you think it's safe to add the return types.

Tests will be probably fixed with symfony/symfony#43917

[malarzm]

• DocumentType should be "extended" in a symfony/form-type-way (`::getParent() method IIRC) so this should be safe.
• MongoDBQueryBuilderLoader how this is solved for ORM?

[franmomu]

• MongoDBQueryBuilderLoader how this is solved for ORM?

It's in Symfony 😬

[jordisala1991]

@franmomu it does not seem that your PR (symfony/symfony#43917) is getting merged for 5.4 or 6.0 (it is target to 6.1), does that affect this PR in any way?

We only miss this one to add sf 6 to three more Sonata bundles.

[franmomu]

@franmomu it does not seem that your PR (symfony/symfony#43917) is getting merged for 5.4 or 6.0 (it is target to 6.1), does that affect this PR in any way?

I've written a comment there, thanks for pointing that out.

In any case, that's when using auto_mapping, we can always set it explicitly, I'll try to change it later today or tomorrow to see if it passes the tests.

[malarzm]

@franmomu I think let's add the types everywhere, let's just put it to the UPGRADE file that in an (unlikely ;) ) event somebody did extend our classes, they need to adjust their code. It's a small BC break they'll need to live with :)

[franmomu]

@franmomu I think let's add the types everywhere, let's just put it to the UPGRADE file that in an (unlikely ;) ) event somebody did extend our classes, they need to adjust their code. It's a small BC break they'll need to live with :)

👍 I think it's unlikely to happen too, now we need #713 first

[malarzm]

#713 merged :)

[franmomu]

All 🟢 now!

[malarzm]

🎉

[malarzm]

Thanks @franmomu!