This commit adds initial support for passing null as a valid value for color properties.
When a color property is applied, if it wasn't specified then the default color is applied. Now, when null is passed, no color will be applied
leaving the last color applied as is.

This is useful when showing an Overlay and you'd like to keep the current StatusBar color unaffected. Another usecase would be when you'd like to avoid coloring an icon in BottomTabs.

* 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