Automatically disable flattening of scroll content view children when needed

[NickGerleman]

Summary: There are a couple scenarios where flattening the child of a ScrollView can cause problems.

1. maintainVisibleContentPosition on both Android and iOS rely on reading live positions in the view tree
2. snapToAlignment on Android uses live view tree, for items to snap to. iOS seems to have very different behavior, and aligns assuming that children are scroll view height, or that a snap interval has been set.

This change adds a prop collapsableChildren which can be used to disable children of scroll content view from being collapsed.

Differentiator is... complicated... but we can mostly just adapt the code dealing with existing traits at the surface level.

Differential Revision: D56226241

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	19,410,732	-47
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	22,784,375	+78
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: 876914be556ca62d6aa77ec101debf09062b8922 Branch: main

[javache]

Merged as https://github.com/facebook/react-native/commit/7b44c8d1d0a089a766c7eab1b5435b2dbf61454c