PURPOSE:
This commit allows to handle the situation in which the quick access
link is used but the live session is not launched yet, by showing an
appropriate error message and by allowing a user with sufficient rights
to launch the live session directly from the quick access page.
Since a session can be launched multiple times, the error related to
closed sessions has been removed, so that the user with the rights to do
it can also "relaunch" a session if it has been closed before.
Task-2816685
Part-of: odoo/odoo#88434
Adrien Schoffeniels
92704847ed