Make sure that http sessions from other webapps than the cms are also logged out in case they are part of the cms session context

We need the following behavior:

1) when the cms http session is invalidated, also all http sessions belonging to webapps that have their http session tied to the CmsSessionContext of the cms http session need to be invalidated

2) when an http session of a (site) webapp invalidates, it should not have access to the 'data' and 'sharedContextMap' any more in the CmsSessionContext any more