Setup automated tests and linters on CI

Is this a bug report, a feature request, or a question?

Choring! 🧹

I like the project and would like to last long and prosper. That's why I propose to setup a CI (e.g. CircleCI or Travis) that would run following jobs:

• unit/integration tests with Jest – for components and utility functions (feel free to use react-native-testing-library to ease component testing)
• e2e tests with Detox – these are nice because they allow testing on actual device with fake gestures
• ESLint or TSLint - eslint/recommended, eslint-config-react-app and eslint-config-prettier are a good start I think, or we can go with tslint
• type checking – add Flow or TypeScript to the project (Flow is easier to set, but TS gets wider adoption and has lots of 3rd party typings, so you decide)

Unfortunately I likely won't find time to set any of this up, but I wanted to start this initiative anyway, because somebody surely will get some of this done :)

@bd-arc I think the best first step would be for you to set up circle and base on this configuration from react-native-paper, I copy it all the time for new projects :P

Start by reviewing the proposed .circleci/config.yml reference from react-native-paper and the repository's existing test setup. Define which CI provider and type-checking approach to use, then add jobs for Jest, Detox, linting, and type checking. Done means these checks run automatically in CI with documented configuration.