* Replace libsecp256k1 with k256 in beefy-mmr
* Port of FRAME `contracts` benchmarking from `libsecp256k1` to `k256`
* Newtype to allow `Pcg32` rng usage with `k256` in contracts benchmarks
* Use `sp-io::crypto` to generate dummy keys in `contracts` bechmarks
* More compact code
* Cargo fmt
* Build `sp-keystore` only for dev profile
* Move public key generation back to the `map`