Fix parallelism bug in exit processing (#1110)

* Fix parallelism bug in exit processing

Also:

* Remove parallelism for all other operations except deposit merkle proofs
* Improve exit tests
* Fix broken attestation test

Closes #1090

* Allow for generating block/pre/post states from some unit tests (#1123)

* Add post-state checks, comments

* Add state_transition_vectors crate

* Integrate new testing crate with CI

* Add readme

* Add additional valid tests

* Remove ExitTests (they were moved to new crate)

* Small test fixes

* Delete incorrect saturating_sub in slash_validator

And clean-up the balance increase/decrease functions to look more like the spec.

Co-authored-by: Paul Hauner <paul@paulhauner.com>

eth2/utils/bls/src/signature_set.rs

@@ -52,6 +52,7 @@ where {
     }
 }
 
+#[cfg(not(feature = "fake_crypto"))]
 type VerifySet<'a> = (
     &'a RawAggregateSignature,
     &'a RawAggregatePublicKey,
@@ -69,6 +70,6 @@ pub fn verify_signature_sets<'a>(sets: Vec<SignatureSet>) -> bool {
 }
 
 #[cfg(feature = "fake_crypto")]
-pub fn verify_signature_sets<'a>(sets: Vec<SignatureSet>) -> bool {
+pub fn verify_signature_sets<'a>(_: Vec<SignatureSet>) -> bool {
     true
 }