Replace bincode with borsh (#452)

* Add SignalsConfig to chain_spec

* Correct multiexp feature flagging for rand_core std

* Remove bincode for borsh

Replaces a non-canonical encoding with a canonical encoding which additionally
should be faster.

Also fixes an issue where we used bincode in transcripts where it cannot be
trusted.

This ended up fixing a myriad of other bugs observed, unfortunately.
Accordingly, it either has to be merged or the bug fixes from it must be ported
to a new PR.

* Make serde optional, minimize usage

* Make borsh an optional dependency of substrate/ crates

* Remove unused dependencies

* Use [u8; 64] where possible in the processor messages

* Correct borsh feature flagging

substrate/primitives/src/balance.rs

@@ -3,6 +3,9 @@ use core::ops::{Add, Sub, Mul};
 #[cfg(feature = "std")]
 use zeroize::Zeroize;
 
+#[cfg(feature = "borsh")]
+use borsh::{BorshSerialize, BorshDeserialize};
+#[cfg(feature = "serde")]
 use serde::{Serialize, Deserialize};
 
 use scale::{Encode, Decode, MaxEncodedLen};
@@ -13,9 +16,11 @@ use crate::{Coin, Amount};
 /// The type used for balances (a Coin and Balance).
 #[rustfmt::skip]
 #[derive(
-  Clone, Copy, PartialEq, Eq, Debug, Serialize, Deserialize, Encode, Decode, MaxEncodedLen, TypeInfo,
+  Clone, Copy, PartialEq, Eq, Debug, Encode, Decode, MaxEncodedLen, TypeInfo,
 )]
 #[cfg_attr(feature = "std", derive(Zeroize))]
+#[cfg_attr(feature = "borsh", derive(BorshSerialize, BorshDeserialize))]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Balance {
   pub coin: Coin,
   pub amount: Amount,