refactor: add access to token used for magic-link generation

[hf]

Magic links often need to be customized. This PR allows folks to customize the link by providing access to the HashedToken.

EDIT: We changed this to use {{ .TokenHash }} instead. You can add this in your email templates in the Supabase dashboard under the email templating section

[kangmingtay]

As discussed internally, we're gonna add {{ .HashedToken }} {{ .TokenHash }} in the go template and document how to use it in the email templates section in the UI

Can you re-review?

[kangmingtay]

hmm can you also add it to the RecoveryMail, InviteMail, EmailChangeMail and ConfirmationMail?

[github-actions]

🎉 This PR is included in version 2.30.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[liaujianjie]

Is there documentation on how to use this feature on the client-side?

[kangmingtay]

@liaujianjie we haven't updated our docs yet but you can start using it to circumvent the problem where email clients preview the magiclink in the email. This can be done by adding a link in the email template which redirects a user to a page on your site that contains a button that they need to click to "confirm their email". (i.e. <a href="https://your_site_url/confirm_signup?token={{.TokenHash}}&type=signup">Click here to confirm your email!</a>).

When the user clicks on that, they should be redirect to https://your_site_url/confirm_signup where you can grab the query params, reconstruct the actual verify endpoint: https://project_ref.supabase.co/auth/v1/verify?token={{.TokenHash}}&type=signup&redirect_to=xxx and embed the verify link in a button.

[liaujianjie]

@kangmingtay

1. One small quality-of-life improvement suggestion: allow us to reference the site URL in the email templates so that we can construct the URL like <a href="{{.SiteUrl}}/confirm_signup?token={{.TokenHash}}">
   
2. How will redirection work with the use of .TokenHash?

[kangmingtay]

Just checked, actually the site url is already available if you do {{ .SiteURL }}.

How will redirection work with the use of .TokenHash?

Hmm yeah i'll add this to the email templates too so it can be easily referenced. For now, the only way to get it is through the {{ .ConfirmationURL }} which isn't great..