[Supabasejs] support modify fetch option in http request

[zhihengGet]

please consider adding a addHeader helper i.e supabase.from ().select().setFetchOptions

the reason for this is that i need to set 'cf' properties in cloudflare worker for outgoing http req, i want to do it per request not on global level, i can write a fetch function and change supabasejs's global fetch with it but this is not easy to do as i need to write tons of if statement