Support multiple crypto at the same time

[tomusdrw]

For now we want secp256k1, but in the near future we might want to collect two signatures of:
secp256k1 and BLS for instance. Later on we might add some ZK stuff.

The protocol should be ready to upgrade to include a new crypto. Gossip messages should contain ALL required signatures.

Different crypto will require different start blocks and also might move at different cadence (for instance ZK stuff, since it's heavy might only be possible once per epoch).

[seunlanlege]

This is technically dependent on #198

[tomusdrw]

This is technically dependent on #198

Not really, no. The payload has nothing to do with the signatures.

[seunlanlege]

Ah well, but this is more future forward looking right? or is BLS already implemented for schnorr signatures in rust?