* Fix `invalid transaction price` error message
* Setup Calibrated GasPriceConfig when usd-per-eth is an endpoint
The change will try to check if the specified value is an endpoint.
If the value of `auto` is specified, the default endpoint URL will be used
otherwise, the user-provided value will be taken as-is for an endpoint.
* Use if-let and check for usd-per-eth arg:
1. auto = use etherscan
2. value = use fixed pricer
3. endpoint = use the provided endpoint as-is
* Fix typo in to_pricce error message
* Correct whitespace indentation
* Use arg_usd_per_eth directly
