PHPStan - Ensure Subscribers Are Registered as Shared

[CrochetFeve0251]

Is your feature request related to a problem? Please describe.
When registering a subscriber we don't want to load it twice.
Due to that we need to make it shared.
Describe the solution you'd like
A custom PHPStan rule should be created to and make sure each time a class implements Subscriber_Interface we are sharing it.
Otherwise, raise an error.
Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.