ff 0.13 (#269)

* Partial move to ff 0.13

It turns out the newly released k256 0.12 isn't on ff 0.13, preventing further
work at this time.

* Update all crates to work on ff 0.13

The provided curves still need to be expanded to fit the new API.

* Finish adding dalek-ff-group ff 0.13 constants

* Correct FieldElement::product definition

Also stops exporting macros.

* Test most new parts of ff 0.13

* Additionally test ff-group-tests with BLS12-381 and the pasta curves

We only tested curves from RustCrypto. Now we test a curve offered by zk-crypto,
the group behind ff/group, and the pasta curves, which is by Zcash (though
Zcash developers are also behind zk-crypto).

* Finish Ed448

Fully specifies all constants, passes all tests in ff-group-tests, and finishes moving to ff-0.13.

* Add RustCrypto/elliptic-curves to allowed git repos

Needed due to k256/p256 incorrectly defining product.

* Finish writing ff 0.13 tests

* Add additional comments to dalek

* Further comments

* Update ethereum-serai to ff 0.13

crypto/dkg/src/tests/mod.rs

@@ -36,7 +36,7 @@ pub fn recover_key<C: Ciphersuite>(keys: &HashMap<Participant, ThresholdKeys<C>>
   assert!(keys.len() >= first.params().t().into(), "not enough keys provided");
   let included = keys.keys().cloned().collect::<Vec<_>>();
 
-  let group_private = keys.iter().fold(C::F::zero(), |accum, (i, keys)| {
+  let group_private = keys.iter().fold(C::F::ZERO, |accum, (i, keys)| {
     accum + (lagrange::<C::F>(*i, &included) * keys.secret_share().deref())
   });
   assert_eq!(C::generator() * group_private, first.group_key(), "failed to recover keys");