Refactoring the continue/is_valid test to remove
the confusing data provider work around, while
still keeping redundancies down to a minimum.
PHPBB3-11615
Due to an auth_refactor, there is a new dependency
in session.php on phpbb_container and a provider.
For purposes of testing, implemented a simple one.
PHPBB3-11620
PHPBB3-11015
This allows us to just create the object without having to include the
driver first. However, it also means that users must specify the full
class name in config.php
* develop-olympus:
[ticket/10052] Add comments to the session testable factory.
[ticket/10052] Correct session tests, and separate session factory from tests
