[server/session] Implement anonymous_session
Now we have a simple rule to compute if a session is anonymous we can implement
the property for server session too. Having it on server side session will helps
the rework of the API to access repository. The new schema drop the concept of
DBAPISession and use server side session for the same purpose.
Related to #2953943
Related to #2503918
from os.path import join
assert __file__.endswith(join('scripts', 'script1.py')), __file__
assert '__main__' == __name__, __name__
assert [] == __args__, __args__