The following PR introduces improved support for Context api and other api's which wrap the root view.

## Context api
Navigation.registerComponent('navigation.playground.ContextScreen', () => (props) => (
  <TitleContext.Provider value={'Title from Provider'}>
    <ContextScreen {...props} />
  </TitleContext.Provider>
), () => ContextScreen);

## Redux
Navigation.registerComponent('navigation.playground.ReduxScreen', () => (props) => (
  <Provider store={reduxStore}>
    <ReduxScreen {...props} />
  </Provider>
), () => ReduxScreen);

## Plain Component - not changed
Navigation.registerComponent('navigation.playground.MyScreen', () => MyScreen);

This PR also upgrades the TypeScript version to 3.2.0 and RN version used in the playground app to 0.57.7

* New Android build flavor - `reactNative57_7`
* Unit test coverage is disabled, for some reason it broke after upgrading to RN 0.57.7

* Refactor peek and pop

* Rollback some XCode stuff

* Added tests for touchablePreview event

* Also fixing searchbarcancelpressed event

* Making sure tests work

This reverts commit 4c519acae8.

* Refactor peek and pop

* Rollback some XCode stuff

* Added tests for touchablePreview event

* Also fixing searchbarcancelpressed event