DevKit updates for 4.x branch

[VincentLanglet]

To fix such PR, I did:

• allow rector ^0.18
• composer update (last rector version is needed for a bugfix)
• Make rector
• replace every (): \Iterator to (): iterable
• replace return array<array to return iterable<array
• run make cs-fix-php
• check phpstan/psalm

cc @core23