Allow to disable all E-Mails / Ghost SMTP

I get that, to get started, the built-in Supabase Mailing System can be helpful. However, most definitely there should be a way to let all E-mail requests go to nirvana. Here's why: Many production apps want to send their own E-Mails with their own templates created in Brevo, Mailjet, rapidmail, whatsoever. I think I don't have to explain why (tell me and I'll provide a massive amount of arguments). Essentially, that makes the built-in mailing system _useless_ for those (which I assume are many). Even more so potentially dangerous or at least corrupt, depending on how I architect the application. Let me give a quick elaboration on that: I have built a specific OTP system which requires specific steps to be able to login. Obviously I do use the verifyOtp for that but there's steps in between. Thanks to the built-in mailing system someone can easily connect to Supabase with the Anonymous Client and bypass my additional mechanisms by using the built-in magic…