Pre-populate users sessions

[php-coder]

Integration tests benefit from this change because it will be possible to not login as a user but use user's session id.

The following classes could be used as a starting point: SessionManagementFilter, SessionAuthenticationStrategy, and SecurityContextRepository

[php-coder]

Perhaps, we can configure Jetty for that:

• https://www.eclipse.org/jetty/documentation/9.4.x/session-management.html
• https://www.eclipse.org/jetty/documentation/9.4.x/configuring-sessions-jdbc.html

[php-coder]

Might be helpful: https://docs.spring.io/spring-security/site/docs/4.2.13.RELEASE/apidocs/org/springframework/security/core/session/SessionRegistry.html#registerNewSession-java.lang.String-java.lang.Object-