This commit also consolidates index files in the playground app

* Cover OverlayManager with unit tests
* Add e2e to test Overlay unmount

* Assign commandId to async commands

* CommandListener refactor

Pull listener out of Navigator and implement NativeCommandListener for native commands

* Emit onNavigationEvent when commands complete

* Rename timestamp to completionTime

* Rename NavigationEvent to EventEmitter

* Rename sendOnNavigationButtonPressed to emitOnNavigationButtonPressed

* Emit navigationEvent on bottom tab select

* rebase fix

* Emit commandCompleted event instead of nativeEvent

* fix native ios commands

* wait show and dismiss Overlay

Both events broke in 104e3f97

We need this constructor to be accessible in order to integrate with CodePush

These two functions were related to previous modal implementation which relied on Dialogs

The reload listener currently doesn't properly pickup reloads from debug menu

* Revert "Fix custom top bar from disappearing after a push (#3109)"

This reverts commit 0e11b95f85.

* Revert "Fixes NPE when initializing twice (#3128)"

This reverts commit 0bf0751f5d.

When modalPresentationStyle is overCurrentContext - previous view is not detached when showing modal.

Add previous view (modal or root) back to hierarchy in ModalPresenter.
Later on this will be controlled by modalPresentationStyle