Make coin a dedicated library

Closes https://github.com/serai-dex/serai/issues/128.

processor/src/lib.rs

@@ -5,8 +5,9 @@ use thiserror::Error;
 
 use frost::{curve::Curve, FrostError};
 
-mod coin;
+pub use serai_coin as coin;
 use coin::{CoinError, Coin};
+
 mod wallet;
 
 #[cfg(test)]
@@ -29,10 +30,3 @@ pub enum SignError {
   #[error("network had an error {0}")]
   NetworkError(NetworkError),
 }
-
-// Generate a static view key for a given chain in a globally consistent manner
-// Doesn't consider the current group key to increase the simplicity of verifying Serai's status
-// Takes an index, k, for more modern privacy protocols which use multiple view keys
-pub fn view_key<C: Coin>(k: u64) -> <C::Curve as Curve>::F {
-  C::Curve::hash_to_F(b"Serai DEX View Key", &[C::ID, &k.to_le_bytes()].concat())
-}