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/amount.rs

@@ -6,6 +6,9 @@ use core::{
 #[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};
@@ -19,20 +22,11 @@ use scale_info::TypeInfo;
 pub type SubstrateAmount = u64;
 /// The type used for amounts.
 #[derive(
-  Clone,
-  Copy,
-  PartialEq,
-  Eq,
-  PartialOrd,
-  Debug,
-  Serialize,
-  Deserialize,
-  Encode,
-  Decode,
-  MaxEncodedLen,
-  TypeInfo,
+  Clone, Copy, PartialEq, Eq, PartialOrd, 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 Amount(pub SubstrateAmount);
 
 impl Add for Amount {