Implement ScrollView sticky headers on Android

Summary:
This adds support for sticky headers on Android. The implementation if based primarily on the iOS one (https://github.com/facebook/react-native/blob/master/React/Views/RCTScrollView.m#L272) and adds some stuff that was missing to be able to handle z-index, view clipping, view hierarchy optimization and touch handling properly.

Some notable changes:
- Add `ChildDrawingOrderDelegate` interface to allow changing the `ViewGroup` drawing order using `ViewGroup#getChildDrawingOrder`. This is used to change the content view drawing order to make sure headers are drawn over the other cells. Right now I'm only reversing the drawing order as drawing only the header views last added a lot of complexity especially because of view clipping and I don't think it should cause issues.

- Add `collapsableChildren` prop that works like `collapsable` but applies to every child of the view. This is needed to be able to reference sticky headers by their indices otherwise some subviews can get optimized out and break indexes.
Closes https://github.com/facebook/react-native/pull/9456

Differential Revision: D3827366

fbshipit-source-id: cab044cfdbe2ccb98e1ecd3e02ed3ceaa253eb78

ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java

@@ -53,6 +53,7 @@ public class ReactShadowNode extends CSSNode {
   private boolean mNodeUpdated = true;
 
   // layout-only nodes
+  private boolean mShouldCollapseChildren;
   private boolean mIsLayoutOnly;
   private int mTotalNativeChildren = 0;
   private @Nullable ReactShadowNode mNativeParent;
@@ -367,6 +368,14 @@ public class ReactShadowNode extends CSSNode {
     return mIsLayoutOnly;
   }
 
+  public void setShouldCollapseChildren(boolean collapsable) {
+    mShouldCollapseChildren = collapsable;
+  }
+
+  public boolean shouldCollapseChildren() {
+    return mShouldCollapseChildren;
+  }
+
   public int getTotalNativeChildren() {
     return mTotalNativeChildren;
   }