* 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
