Setup Jest files and Enable Coverage

Background:

Fix failing test on RegisterScreen and add setupfile to easily add mocks. Enables code coverage too in ./jest/coverage/*

Added packages:

• redux-mock-store (dev)
• jest-expo (dev)

How to test:

Run yarn test and see coverage folder in ./jest. Testing components that have a redux hook and navigation useNavigation() hook also works now.

Tested on:

• iOS
• Android