[Chains/BNBGreenfield]: Add BNB Greenfield

[satoshiotomakan]

Description

Add support for BNB Greenfield: https://greenfield.bnbchain.org/
Greenfield is a Cosmos-like blockchain. At this moment, Greenfield supports only EIP712 signing mode, i.e. to sign a transaction, it's needed to convert the original TxRaw protobuf message to a Typed Structed data (EIP712), hash it and sign by using secp256k1 curve.

How to test

Run C++, iOS, Android, WASM tests

Types of changes

Add Greenfield Cosmos-like blockchain with only Send message.

Possible improvements

The process of converting TwRaw protobuf package into a Typed Structed data (EIP712) is tricky.
The code is available here: link.

It would be great to implement this algorithm in the future. But for now, we use pre-defined hardcoded Msg1, TypeMsg1Amount type names.

Checklist

• Create pull request as draft initially, unless its complete.
• Add tests to cover changes as needed.
• Update documentation as needed.
• If there is a related Issue, mention it in the description.

If you're adding a new blockchain

• I have read the guidelines for adding a new blockchain.

[Milerius]

Good job, just one minor comment