No validation hook for Custom SMS Hook

# Bug report <!-- ⚠️ We receive a lot of bug reports which have already been solved or discussed. If you are looking for help, please try these first: - Docs: https://docs.supabase.com - Discussions: https://github.com/supabase/supabase/discussions - Discord: https://discord.supabase.com Before opening a bug report, please verify the following: --> - [x] I confirm this is a bug with Supabase, not with my own application. - [x] I confirm I have searched the [Docs](https://docs.supabase.com), GitHub [Discussions](https://github.com/supabase/supabase/discussions), and [Discord](https://discord.supabase.com). ## Describe the bug I have read the Supabase SMS Hook documentation here: https://supabase.com/docs/guides/auth/auth-hooks/send-sms-hook. The hook is a Deno server which gets called with an object containing the SMS OTP (under sms.otp property). However, this is inadequate to support SMS OTP providers which are similar to Twilio Verify, in which it has an endpoint for sending the OTP, and another endpoint for validating, and throughout the process the correct OTP cannot be set by, and is unknown to the developer. Such platforms include [Message Central VerifyNow](https://www.messagecentral.com/product/verify-now/overview) and [Plivo](https://www.plivo.com/docs/programmable-api/verify/overview). With current SMS Hook, it is impossible to support such providers because: - We cannot set the OTP involved and can only control the sending and validation - There is no similar hook for OTP validation ## To Reproduce - Go to documentation at https://supabase.com/docs/guides/auth/auth-hooks/send-sms-hook - Try sending the OTP with abovementioned or similar platforms - Realise that there is no verify OTP hook ## Expected behavior A verify hook is provided. This flow can also support use cases where the developer has full control over the message contents. ## Screenshots If applicable, add screenshots to help explain your problem. ## System information - OS: Linux - Versi…