Add styles for React and React Native

[purinkle]

We have some loose guides on how we write our JavaScript, but we are not detailing how we expect React and React Native components to be written. This could lead to inconsistencies across projects. We should add styles for React and React Native components.

[rakeshpetit]

https://trello.com/b/Cmeo01g1/react-reference-app - I think this trello board has some interesting opinions for React web. Styled components seem to be favoured by a lot of developers for styling. My opinion on React components would be that in 2019 we should be using functional components leveraging hooks as much as possible. It would be interesting to know if developers faced any hiccups with functional components(with hooks) and had to resort to using class-based components instead.

[WilHall]

I recently created #603 for web React/TypeScript apps before seeing this issue; it's not quite completed yet, but I wanted to get my thoughts down based on my experience over the past year.

I would love some early 👀 from anyone who is interested in this stack!

I'm also playing around with a proof-of-concept suspenders-like thing for React apps, which will be here: https://github.com/thoughtbot/react-suspenders

@stevehanson has also created a React Reference App: https://github.com/thoughtbot/react-reference-app

He may have thoughts here as well 🙂

[johnschoeman]

Getting a guide for RN started here: #633

Would also love some early 👀 for anyone interested!

[johnschoeman]

A React Native guide was introduced here: #633
The React guide was introduced here: #603
While the original issue mentioned React components in particular, I believe the spirit of the issue has been addressed by adding the React and React Native guides themselves.