Feature/optional unity loader

[jeffreylanters]

Before submitting a pull request, please make sure the following is done:

• Fork the repository and create your branch from master.
• Run npm install in the repository root.
• If you've fixed a bug or added code that should be tested, using the test environment.
• Ensure the test suite passes using npm test on the library.
• Ensure the test suite passes using npm start on the test environment and check if everything works.
• Format your code with prettier.
• Make sure your code lints (ts lint).
• Typecheck all of your changes and make sure JSDocs are provided.
• If you haven't already, complete the CLA.