Registration with email verification process

[jean-michelet]

We should wait for #48 to be merged.

Currently we use a basic username for login, we should use an email.
Migrations, seed-database.ts and tester helper must be updated before proceeding.

[AxelVilleret]

Hey ! Can you assign me this issue ?

[Fdawgs]

Hey ! Can you assign me this issue ?

We don't assign issues as we find it discourages others from fixing/implementing changes.

[EnzoDOROSARIO]

Is the goal to replace username-based login with email authentication, so we can then implement the registration process with email verification ?

[jean-michelet]

It could be done without changing the username-based login. The goal here is to validate someone email. But I think we should use an email for authentification too, as most of users are used to login/register this way, plus it's already a unique identifier. They can update their username once registered on their profile if necessary.

[EnzoDOROSARIO]

I've created an initial PR that adds an email field for users, which we can use as a foundation for further iterations.