This resolves an issue where currentTabIndex, for example, was not cleared properly
if it was set in initialOptions as it was cloned each time clearOptions was invoked.

This commit introduces an option to control the way components are pushed into the stack.
When pushing components into a stack, they are pushed the moment they are measured.
If `waitForRender` is true, components will be pushed only after the initial render.

api:

```js
options: {
  animations: {
    push: {
      waitForRender: true
    },
    showModal: {
      waitForRender: true
    }
  }
}
```

* Refactored bottomTab and bottomTabs

* Initial commit before switching to our fork of AHBottomNavigation

* Bump AHBottomNavigation version

* More work on BottomTab options

Need to merge some child options when a child is attached to parent

* Fix tests

* DefaultOptions refactor

* defaultOptions are now merged before applying options
* Handle BottomTab options in dedicated presenter
* Create BottomTabs in BottomTabsController.createView() instead of constructor

* Set bottomTab TypeFace

* Update Android installation guide

* fixed unit tests

* Fix unit tests

Kind of a workaround

* Handle NPE in getPreferredHeight

If a view hasn't been attached yet, return 0 height

* Apply BottomTab text and icon color individually

wix-playground/AHBottomNavigation does not support setting color for the entire tab (icon and text),
instead it supports setting color individually to text and icon. Another change is that it no longer supports
default color for icons. If icon color is undefined - it won't tint the icon.

* Add getCurrentChild to ParentController contract

* Clear backButton when setting stack root

* Add  ViewController.resolveCurrentOptions

resolveCurrentOptions merges the controllers options with all of its current children

* StackController refactor

* Create pushed child view only in StackController.createView
* When initialising a stack with multiple children, only create the top child's view
* StackController constructor now accepts children
* When pushing child to stack, apply options that change LayoutParams

* Apply BottomTabs layout options when tab views are created

* bototmTab changes in iOS

* options fix

* Fixes options propagating

* Refactored backButton api

* Move StackController to separate package

Implement BackButtonOptions

* Somewhat simplify StackController creation in tests

* Pull backButton logic from StackController

* Handle all TopBar button options in TopBarButtons

* fix back button on iOS

* Set default statusBarBackgroundColor to Black
* Component and Parent controllers now extend ChildController
* Implement return to front logic for ChildControllers
* Apply statusBar color when view appears and returns to front

Previously, all options were cleared and reapplied whenever mergeOptions was called

* External Component implementation

* Limit External component e2e to Android for now

* Initial implementation of willAppear and willDisappear

Currently only implemented on pop in StackController

* call clearOptions on super
* TopTabs visible

* fix unit

* applyOptions is applied in correct order

* Use AHBottomNavigation for BottomTabs

* Process passed options for all layout types

Static options are still processed only for components

* ios e2e fix

* Update RNNNavigationController.m

* Change topBar backgroundColor to Color object

* StackLayout implementation

Unfortunately, this commit also contains a lot of refactoring and a few
bug fixes relating to styles.

* TopBar is not part of Component, instead it's a part of StackLayout
  and shared between all components pushed to the stack Similar to iOS.
* Handle ScrollEvent in ReactView instead of passing the listener down
* Implement Fraction and Text null objects for style params
* Converted a few style params to null objects. This fixes some styles
  being applied even when they were not specified explicitly.
* Stop sending null promise to commands
* Seperate push and pop into animatePush/push and animatePop/pop
  to avoid boolean param

* Adapt TopTabs to new API

* Further work on TopTabs and some refactoring

* OptionsPresenter receives views as params
* Remove TopBar and style logic from ViewControllers, these are the OptionsPresenters concern
* StackAnimator isn't coupled to LinearLayout
* Convert Runnable to lambda
* ContainerLayout now implements ReactContainer interface
* Enable desugaring in playground app

* TopTabs unit tests