IBX-9727: Add missing type hints to PAPI events

[adamwojs]

🎫 Issue	IBX-9727

Description:

• Narrowed down return type from iterable to array in \Ibexa\Contracts\Core\Repository\UserService::{deleteUser, deleteUserGroup} methods
• Narrowed down return type from iterable to array in Ibexa\Contracts\Core\Repository\ContentService::deleteContent method
• Add missing type hints to PAPI event structs

For QA:

N/A

Documentation:

N/A

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.2% Duplication on New Code

See analysis details on SonarQube Cloud

[alongosz]

+1 for iterable -> array change

+1 for the other changes based on diff with my previous work on branch ibx-8471-symfony-7-full - though that's technically +1 to my own code ;)