The default value for `UITabBarItem.title` is `nil` as specified by the docs:
> You should set this property before adding the item to a bar. The default value is nil.
https://developer.apple.com/documentation/uikit/uibaritem/1616412-title

This changes allows for this to be `nil`.

* bind viewController to presenters using bindViewController

* Merge options to the specific provided layout

* Moved custom titleView creation to RNNRootViewController

* Moved default options to presenters, moved options applying to presenters, resolved options in RNNOptionsResolver

* Fixes merge options

* Fixes topBar transition on pop

* Prevent titleView creation when react titleView exists

* Fixed unit tests

* Options refactor WIP

* Detach applied options from DTO - WIP

* Added option types and option parsers

* Unit test passes

* Added presenters for each parent type

* Fixes unit tests

* Rename StringParam to Text, changed bottomTabs.drawBehind and topBar.drawBehind default to false

* set layout.backgroundColor default to white

* Added unit tests for RNNViewControllerPresenter

* Set layout.backgroundColor default nil

* Fixes buttons color missing options

* Fix unit test

* fix button color parsing

* Moved default options to presenters

* default options fixes

* Fixes e2e

* Fixes unit tests

* Resolve child options on childWillAppear

* Recrusively setDefaultOptions on rootViewController tree

* Fixes default values

* Fixes tests