MODE-1924 Changed AuthorizationProvider framework to always use absolute paths

Most of the time ModeShape was passing absolute paths to the AuthorizationProvider. However, in some places ModeShape passed relative paths, and this makes it very difficult for implementations to properly check permissions.

This behavior was changed so that ModeShape always passes absolute paths.
MODE-1924 Added AdvancedAuthorizationProvider

A new AdvancedAuthorizationProvider interface was added, where this new interface now provides access to the Session through a new context mechanism (which can be used in the future to add more parameters without breaking API compatibility).

The Session now simply does one extra instanceof check when attempting to determine the permissions.
MODE-1924 Renamed parameter to make it clear we pass the absolute path.