Lib.rs

This project is used to build transactions for ethereum chains.

EthereumTransactionBuilder:

Its implementation of `TransactionBuilder` and implements the following methods:
1. `transfer`
2. `method_call`
3. `create_and_sign`

transfer:

Creates `EthereumMetadataParams` for transfer call.

method_call:

Creates `EthereumMetadataParams` for contract calls. It takes 
`method`: this is a string contraining contract address and method signature with `-` seperation.
`params`: array of json_value with params taken by contract methods in string format.

It returns `EthereumMetadataParams` with `data` field set to the encoded contract call params.

create_and_sign:

When `metadata` is created we use this call to create Ethereum Transaction and sign it. It takes following arguments.
`config`: chain sepecific config.
`metadata_params`: Metadata params which created metadata for this call.
`metadata`: Metadata required make transaction.
`secret_key`: wallet's secret key (used to sign the transaction).

It creates the transaction and signs it and then returns its bytes.