fix(iOS, SplitView): Break the retain cycle between component and controller for SplitViewScreen

[t0maboro]

Description

Closes:
https://github.com/software-mansion/react-native-screens-labs/issues/156

Problem:

• Controller has a strong reference to an associated component via .view property.
• In our case, Component keeps a strong reference to the controller.
• This creates a retain cycle, which we're not breaking anywhere at the moment.

Solution:
SplitViewHost keeps references to all subviews of type SplitViewScreen all the time (columns might be hidden, but they won't disappear). It means that we can consider Host as an owner of the SplitViewScreens' lifecycles. If the host is about to be unmounted from the view hierarchy, we can perform some additional cleanup in child components to detach the reference to theirs controllers.

Changes

• Added a method for invalidating a screen component that removes a reference to the controller.

Test code and steps to reproduce

Create an example that includes a SplitView, which may be removed from the hierarchy, add log and observe.

Checklist

• Included code example that can be used to test this change
• Ensured that CI passes

[kkafar]

Added clarification comments. I'd also move the for loop that invalidates the children into separate method, e.g. invalidate :D

[kkafar]

Thanks!

Let's do something similar for bottom tabs implementation (in separate PR obviously)

[t0maboro]

Thanks!

Let's do something similar for bottom tabs implementation (in separate PR obviously)

#3085 - created a followup for bottom tabs