flashbots/contender

AI Summary: The user requests a new feature allowing environment variables, defined in a scenario's `[env]` configuration, to be used within the `from` address field. This is intended to provide more flexibility for quick setups, debugging, and testing, especially when the `from_pool` option is insufficient.

AI Summary: The task is to modify the `contender admin accounts` command to display both the addresses and private keys of generated accounts. This involves updating the command's logic to retrieve and format the private keys alongside the addresses, and potentially enhancing output formatting for improved readability.