(doc): improve IService doxygen about output management

Description

Describe how to properly remove the service's outputs and why and when we should do it.

Add a check when the service is unregistered and destroyed to verify if it owns an output that will also be destroyed (if the output pointer is only maintained by this service). Currently only an error log is displayed, but it may be replaced by an assert later. Other services may work on this object but didn't maintained the pointer (they used a weak pointer).

Closes #563 (closed)

How to test it?

Launch any application, it should work as before but an error log maybe displayed.