Dissociate Submits and Talks

[HedicGuibert]

Currently, Talks don't have any relation with Users besides submits, making it impossible to know who created a talk if this talk was never submitted.
As a result, we currently have many talk with no user related to them in the production database.

Another consequence of this is that in the user account, users can only create a Talk if they submit it at the same time.
Or we can only show them the talks they already submitted in their talks page.

This would be way better if a talk directly had a column referencing the user that created it.

[lyrixx]

This would be way better if a talk directly had a column referencing the user that created it.

YES 👍🏼