Upgrade to Schnorr/FROST/ROAST

[erdogan]

We need an MPC algo that is resilient to in-group aborts / DoS at wallet creation and signing time.

Our two candidates are CGGMP21, a complex ECDSA protocol we’ve put a lot of time into... and FROST / Schnorr, a simpler MPC protocol for Schnorr signatures that might require additional wallet revamping.

[mhluongo]

... and we've got an implementation!

https://github.com/threshold-network/roast-go