Expose cleanupContentsNodesRecursively for backport

Backport prerequisite: make cleanupContentsNodesRecursively externally
linkable and declare it in CalculateLayout.h so AbsoluteLayout.cpp can
call it. This mirrors the relevant slice of #55876 (26cef64), which
is not present on this branch, and is required before applying #56422
and #57103.

Author: j-piasecki

packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp

@@ -480,7 +480,7 @@ static void zeroOutLayoutRecursively(yoga::Node* const node) {
   }
 }
 
-static void cleanupContentsNodesRecursively(yoga::Node* const node) {
+void cleanupContentsNodesRecursively(yoga::Node* const node) {
   if (node->hasContentsChildren()) [[unlikely]] {
     node->cloneContentsChildrenIfNeeded();
     for (auto child : node->getChildren()) {

packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.h

@@ -35,4 +35,6 @@ bool calculateLayoutInternal(
     uint32_t depth,
     uint32_t generationCount);
 
+void cleanupContentsNodesRecursively(yoga::Node* const node);
+
 } // namespace facebook::yoga