Adds a modules array that can be used in @storybook/react-native v6

[gezquinndesign]

loadStories() and stories are of no use in storybook for react-native v6, so I've just added this additional export that can be used instead of loadStories in configure, eg:

import { modules } from './storyLoader';
...
configure(( ) => {
   return modules
}, module)