ethers::utils::format_ether should show decimal places

[0xAndoroid]

Motivation

Well, I've just spent 30 minutes trying to understand why I see 0 ETH as the output of my code. Turns out, it was a problem in prase_ether function. Noticed an issue #2356

Solution

Use parse_units(value, "ether").unwrap();
We can safely unwrap here, since parse_units returns Err only when units >= 77.

PR Checklist

• [ x ] Added Tests
• [ x ] Added Documentation
• [ x ] Breaking changes

[DaniPopes]

This is great, thanks! It's a small enough breaking change that I'm OK with releasing this in a patch or minor version, wdyt @gakonst @prestwich?

[prestwich]

This is great, thanks! It's a small enough breaking change that I'm OK with releasing this in a patch or minor version, wdyt @gakonst @prestwich?

agreed