fix(PointAnnotation): fix nested children not rendering on New Architecture (Fabric) (#4231)

* fix(PointAnnotation): wrap children in non-collapsable View to fix Fabric view flattening

In React Native's New Architecture (Fabric), a View inside PointAnnotation
can get its children lifted up to become direct siblings in the native child
list. This triggers the "supports max 1 subview" error and causes the bitmap
snapshot to miss nested children (text labels disappear, only the empty outer
View is captured).

Wrapping content children in a View with collapsable={false} prevents Fabric
from flattening the user's View, so the native layer always sees a single
content child regardless of nesting depth.

Also removes the manual collapsable={false} workaround from the
PointAnnotationAnchors example, since the library now handles it.

Fixes #3682

* simplify callout/content split in PointAnnotation render

---------

Co-authored-by: Miklós Fazekas <boga@MBPM5P.local>