Create the session and domain directories on start

When the session starts, we now create the <session-name> folder and the
domain folder(s) regardless of the activity or registered apps.

This will be useful for the session rotation feature to avoid dealing
with empty rotations. Also, it is more consistent for the user to have
an empty trace folder instead of no folder at all if a session is
completely inactive.

This also removes the directory creation made by the session daemon
which did not belong there.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>