refactor: rewrite and prepare for release

[mcataford]

Big bang rewrite;

• Replaces regexp usage with Babel parser to find imports within source files
• Replaces manual package.json fetching with yarnpkg project discovery

To do:

• Restore test coverage without mocks
• Fix types

Addresses

• Spruce up the standard output #4
• Sort up CI #3

[mcataford]

@all-contributors please add @noahnu for build

[allcontributors]

@mcataford

I couldn't determine any contributions to add, did you specify any contributions?
Please make sure to use valid contribution names.

[mcataford]

@all-contributors please add @noahnu for code

[allcontributors]

@mcataford

I've put up a pull request to add @noahnu! 🎉