This option allows to control when tab titles are displayed

* showWhenActive: when a tab is focused
* alwaysShow: show regardless of which tab is in
* alwaysHide: never show tab titles

This commit also changes the way TopTabs options are handled. As the TabLayout
is part of the TopBar, it's the StackControllers responsibility to set TopTabs options.

Hopefully increasing button size will eliminate flakyness

* V2: Peek and pop

* Add event when preview is dismissed in non commit mode

* tslint

* Refactor playground. Document preview api

* Added width prop

* Implement hybrid push/preview button

* Fixing small linting errors

* Testing new multi pr job

* Disable unmounts when dismissed

This works around an issue with RN's view reconciliation when the
root component has no background color defined.

This option property lets us set a top margin to a component which can be useful sometimes
when using statusBar.drawBehind.

screenBackgroundColor was also renamed to backgroundColor

```js
layout: {
  orientation: 'landscape',
  backgroundColor: 'red'
}
```

* Work in progress

* Arbitary changes

* Improvements on API

* Cleanup RNNSplitViewController, allow mergeOptions

* Added documentation and better playground example

* Adding tests for coverage

* Find out why this test is failing.

* Only show split view on iOS

* Add test back in

Hopefully, this will prevent Detox from timing out when a system alert pops up on the screen.

This commit add support for changing the TopBar height as well as changing
the height of custom component used as background

1. Sideenus weren't clickable on Android. It seems the order in which
child views were being added to parent controllers, left or right
before center, were affecting the ability to interact with the menus.
I've changed the code to always add them in a specific order: center,
then left, then right.

I believe this closes issue #2835.

  https://github.com/wix/react-native-navigation/issues/2835.

2. On Android, merging options to open a menu works.

  Navigation.mergeOptions(currentComponentId, {
      sideMenu: {
          left: {
              visible: true
          }
      }
  })

But merging options to close it wasn't working.

  Navigation.mergeOptions(currentComponentId, {
      sideMenu: {
          left: {
              visible: false
          }
      }
  })

3. The bottom tabs controller was reserving a margin space for the tabs
when switching from one to another, regardless of its visibility
settings.

As you can see here: https://github.com/wix/react-native-navigation/blob/v2/lib/src/events/EventsRegistry.ts#L28 nativeEventListener expects an object which is includes name and params but on the iOS side, the native bridge is triggers the event listener but passes wrong object. iOS is passes commandName instead of name. This commit is fixes the problem.

* setRoot({root:{}})

* support setRoot with root, modals, overlays

* Update setRoot calls in playground app to new api

* Update setRoot on Android to new api

currently only supporting root node

* Update setRoot on iOS to new api

* fix unit tests

* New statusBar options format
* Static events

* refactored status bar options iOS

* [Breaking] Pull StatusBar styles to separate object

Currently exporting `backButton` id, usage: `Navigation.constants.backButton`

Pass child ViewControllers in constructor and create tabs in constructor as well

Fixes #2996