TSAS — 3.4 delete context segment

3.4 delete context segment.
3.4.1.1 delete get_user_context and add exception in set_user_context
(3.4.1.2)

3.4.1.2 set_user_context move to new start segment before start_session.

Remove access_session_id form user_ctxt, it is not needed.

3.4.2.2 get_user_ctxts, is this operation needed? If so, move this to
access session control interface and add an operation list_user_ctxts

3.4.2.3 get_user_info, this is not relevant for the context. Move the
get_user_info to the new start segment. Check the user info structure
with subscription.
Currently they are different.

see above