Replace libsecp256k1 with secp256k1

[bernardoaraujor]

Motivation

Substrate has replaced libsecp256k1 with secp256k1. Apparently, that results in a significant performance improvement: https://github.com/paritytech/substrate/pull/10798

Suggested Solution

Replace the dependencies in frontier, namely:

• fp-rpc: https://github.com/paritytech/frontier/blob/0535842137360e80f36bbe3d6a5333d6ad8b9c8a/client/rpc/Cargo.toml#L20
• pallet-ethereum: https://github.com/paritytech/frontier/blob/0535842137360e80f36bbe3d6a5333d6ad8b9c8a/frame/ethereum/Cargo.toml#L40

[mahmudsudo]

can i take on this ?