Secp256k1 was removed in the protobuf migration, this pr adds it back in order to provide this functionality for users (band) Closes: #5495
## Description Remove secp256k1 as discussed in the tendermint dev call. The implementation has been moved to the [Cosmos-SDK](443e0c1f89/crypto/keys/secp256k1) Closes: #XXX
443e0c1f89/crypto/keys/secp256k1