Deprecate user_logout() and user_login_finalize() and replace with a service

Problem/Motivation

We are calling the procedural functions user_login_finalize() and user_logout() in user.module.

However, these have a load of dependencies such as

• AccountInterface
• SessionInterface
• SessionManagerInterface
• EntityTypeManagerInterface
• ModuleHandlerInterface
• LoggerInterface

Let's create a service and do proper dependency injection.

Steps to reproduce

Proposed resolution

• create a new \Drupal\user\UserSessionHandlerInterface and \Drupal\user\UserSessionHandler
• define a new 'user.user_session_handler' service
• deprecate user_login_finalize() and user_logout()
• replace all usages in core

Remaining tasks

User interface changes

API changes

• user_login_finalize() and user_logout() are deprecated
• a new 'user.user_session_handler' service is added

Data model changes

Release notes snippet

Original summary

Lets move this somewhere..maybe the User entity controller? i am not really sure cause it has to do with session