s3-auth Use struct auth3_session_info outside the auth subsystem

s3-auth Use struct auth3_session_info outside the auth subsystem

This seperation between the structure used inside the auth modules and
in the wider codebase allows for a gradual migration from struct
auth_serversupplied_info -> struct auth_session_info (from auth.idl)

The idea here is that we keep a clear seperation between the structure
before and after the local groups, local user lookup and the session
key modifications have been processed, as the lack of this seperation
has caused issues in the past.

Andrew Bartlett

Signed-off-by: Andrew Tridgell <tridge@samba.org>