This commit started with a small fix to a TopBar visibility issue detailed in #3971 which unveiled
a few issues with how options are resolved and merged.

TopBar visibility
The initial TopBar visibility issue was a result of hide animators now being cancelled when pushing another screen.
Another issue was that if the TopBar was not measured (Initial stack child was shown with `TopBar.visible = false`),
the start value passed to the Y translation was 0. This commit makes sure the TopBar show animation starts after the TopBar is measured.

Options issues
When resolving current issues in ParentControllers, the options of the current child were wrongfully taken into account.
This commit changes options resolve logic so that initial options (and options dynamically merged to them via mergeOptions call) are merged.