Add iOS support for `bottomTabs.attachMode`.
This property controls when BottomTabs children are attached to hierarchy and when their React views are created.

By default, RNN attaches all children at the same time which might impact loading time as a few screens are instantiated at once.
Using `afterInitialTab` or `onSwitchToTab` generally leads to improved start up time.

* Fix button with react component doesn't get unmounted

* Test e2e only on iOS

* Fix topBar.title.component fill alignment

* Lock react-native-ui-lib version

* Layout changes

* WIP

* Revert "Layout changes"

This reverts commit 4da8cfbd12.

* Clean topBar.component and topBar.background.component when not needed

* Move custom components login from viewController to presenters

* Change waitForRender and enabled property from primitive bool to Bool object

* Fix ios unit tests

* Add unit tests

* Remove RNNReactView observer when view ready

* Load react components from component manager

* Remove createCustomReactView duplication

* Handle render children in each Layout

* Wait for navigation presenter components render, refactor RNNTitleViewHelper

* Fix unit tests

* Add waitForRender for custom react components

* Fixes e2e

* fix custom header

* fix e2e