Allow user authentication from email links

[nicoolas25]

Summary

As part of #829 I would like to authenticate users right from emails. This PR sets the foundations to do this.

So far we authenticated users using matches' tokens or slot_alerts's tokens.
Now we need users' tokens: we need communication unrelated to any of the above events.

Details

No functional changes should be part of this PR.

It adds a concern for controllers UserAuthenticationViaSignedId that complements the usual devise/warden authentication using an authentication_token based on globalid.

It creates a single partial to DRY those routes:

• users#destroy,
• matches/users#destroy, and
• slot_alerts/users#destroy.

Also DRY those views:

• slot_alerts/users#edit, and
• matches/users#edit

... into users/_confirm_destroy_message.

The goal is to reuse confirm_destroy_profile_path from email and sign it with an authentication token.

This users#confirm_destroy action looks like this:

Poke @mininao as you authored the original issue.

The next steps are:

1. Create the rake task to identify the appropriate users
2. Create emails to send to those users, include a link to confirm_destroy_profile_path with an auth token

[nicoolas25]

I inverted those two lines, is that okay?

[nicoolas25]

Here is where the magic happens ✨

[nicoolas25]

I had a flaky spec that I fixed in the last commit.

While running the spec in a loop I had intermittent failures:

[nicoolas25]

Another approach would be to update the randomness seed but it would impact the production code a bit too much so I went for this.

[carsso]

Je t'ai invité sur le repo.
Tu peux faire une branche directement sur le repo pour que les tests puissent tourner ?
généralement on préfixe nos branches avec le pseudo github