Add renderLit to render-component

[geireann]

This PR adds an additional renderLit function into the riteway/render-component path of this package to support Lit elements. The renderLit function takes in an element parameter of type TemplateResult and returns a Cheerio instance that can be used in the exact same way as the previous render for Lit elements.

The default render method will use renderReact and use the previous implementation.

Todo:

• [ ] Add tests (having an issue with ESM vs CommonJS modules)
• [X] Update README

[ericelliott]

We are using renderFixture and renderShadow in our platform repo. Should they be here?