Sample parameters via hash-to-curve

[Pratyush]

Whenever we're sampling group elements in a transparent setup, we should use hash-to-curve instead of sampling the parameters via Rngs

[Pratyush]

@ValarDragon, at some point you were working on hash-to-curve infra, right? Do you know the state of that?

[weikengchen]

It would be great if there is a global macro that helps write hash-to-the-curve, so individual programs just call something like:

hash_to_curve!(G1, format!("Transparent setup {}", i));