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/node/src/chain_spec.rs

@@ -6,7 +6,7 @@ use sc_service::ChainType;
 
 use serai_runtime::{
   primitives::*, WASM_BINARY, BABE_GENESIS_EPOCH_CONFIG, RuntimeGenesisConfig, SystemConfig,
-  CoinsConfig, DexConfig, ValidatorSetsConfig, BabeConfig, GrandpaConfig,
+  CoinsConfig, DexConfig, ValidatorSetsConfig, SignalsConfig, BabeConfig, GrandpaConfig,
 };
 
 pub type ChainSpec = sc_service::GenericChainSpec<RuntimeGenesisConfig>;
@@ -51,6 +51,7 @@ fn testnet_genesis(
         .collect(),
       participants: validators.clone(),
     },
+    signals: SignalsConfig::default(),
     babe: BabeConfig {
       authorities: validators.iter().map(|validator| ((*validator).into(), 1)).collect(),
       epoch_config: Some(BABE_GENESIS_EPOCH_CONFIG),