Changes to session breaks access to masquerading user.

Problem/Motivation

Changes made in the parent issue relating to updating the last access time resulting in internal changes to the storage of the masquerading user's uid. That issue introduced a service with a method to return if is a user is masquerading, but not a public method to return who is masquerading.

My use case is that in some instances the original user should be used, such as when they are sending email on behalf of another user.

Proposed resolution

Simply change the protected method getMasquerate() to public.

This will be backward-compatible with all other modules.