Move verify_share to return batch-verifiable statements

While the previous construction achieved n/2 average detection,
this will run in log2(n). Unfortunately, the need to keep entropy
around (or take in an RNG here) remains.

crypto/frost/src/tests/literal/dalek.rs

@@ -1,4 +1,4 @@
-use rand::rngs::OsRng;
+use rand_core::OsRng;
 
 use crate::{
   curve,

crypto/frost/src/tests/literal/ed448.rs

@@ -1,4 +1,4 @@
-use rand::rngs::OsRng;
+use rand_core::OsRng;
 
 use ciphersuite::Ciphersuite;
 

crypto/frost/src/tests/literal/kp256.rs

@@ -1,4 +1,4 @@
-use rand::rngs::OsRng;
+use rand_core::OsRng;
 
 use crate::tests::vectors::{Vectors, test_with_vectors};