Edit assistant while login feature is disabled

[pocman]

Bug description

The login feature is disabled by default and users are attributed a unique ID based on their browser.
At the moment, any user can delete an assistant but only the user who created the assistant can edit it.
When the user loses the browser context, no one can edit the assistant anymore.

Steps to reproduce

1. Create assistant
2. Edit the assistant
3. Swith to private mode
4. Try to edit the assistant (not possible, button is hidden)
5. Delete the assistant

Fix

We propose to add a env variable to allow any user to edit any assistant.

[Turtleback217]

Note: also, no one can delete an assistant after browser context is lost.