feat: expose SnarkPack for Empty Sector Updates aggregation API

[cryptonemo]

No description provided.

[cryptonemo]

Requires filecoin-project/rust-fil-proofs#1729

[BigLep]

@cryptonemo @vmx : what are the next steps for this?

[vmx]

Short version: Take it and write a FIP etc or leave it.
Longer version: The next steps is for the researchers to decide whether it's worth or not. I think @cryptonemo discussed it a bit in the past with @irenegia and @lucaniz, but there wasn't really time/a decision whether it should be done or not. I think they could also comment on it. @cryptonemo nonetheless decided to try it out, to see how much work it would be and finished it. This is a PR that wires the implementation up to the public API.