Support ganache-cli --secure flag

[EricHuang0525]

Overview

Add support for the --secure flag in ganache. It unlocks default accounts without private keys in the development network. I want to use a default account in accounts to sign a message.

Specification

• Within the cmd_settings config, include "secure".
• If the "unlock" flag also supports unlocking accounts by their index, not only unlock by the account address, it will more helpful.

Reference

Ganache CLI - secure