chore: Add formatter

[jrmykolyn]

Overview:

This pull request introduces the following changes:

• Adds support for formatting via the format script (ie. npm run format).
• Automatically formats source code prior to commit.
• Formats all src/ and config files.

It achieves this by introducing the following dependencies:

• Prettier
• Husky for Git hook manage.

Additional Notes:

• This pull request uses the 'out of the box' Prettier configuration. Additional information about Prettier's configuration options can be found here.
• This pull request appears to be larger, but the it introduces a very small number of material changes. The changes made to the contents of src/ and config/ are programmatic formatting (ie. non-functional).

[joepetrowski]

Thanks for this PR! I'm definitely in favor of adding a formatter. I just did a refactor which led a bunch of conflicts on this branch. Would you mind merging master?

As far as configurations go, I would follow the styles of other Polkadot integration tools like https://github.com/paritytech/txwrapper-core/ and https://github.com/paritytech/substrate-api-sidecar. That said, this prettier config greatly improves readability, would be happy to include this.