Expose box sizing getters and setters in Yoga (#1701)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1701

X-link: https://github.com/facebook/react-native/pull/46630

I would like to write some tests for box sizing that will drive a lot of my development as I implement content box. To do that, I need this publicly exposed. Obviously not that ideal since this currently does not do anything. Maybe we can name the value in such a way that its clear it is in development?

Changelog: [Internal]

Reviewed By: NickGerleman

Differential Revision: D63135970

fbshipit-source-id: 7520823bf925364eae45341531e012e80ec92284

java/com/facebook/yoga/YogaProps.java

@@ -105,6 +105,8 @@ public interface YogaProps {
 
   void setBaselineFunction(YogaBaselineFunction yogaBaselineFunction);
 
+  void setBoxSizing(YogaBoxSizing boxSizing);
+
   /* Getters */
 
   YogaValue getWidth();
@@ -148,4 +150,6 @@ public interface YogaProps {
   YogaValue getPosition(YogaEdge edge);
 
   float getBorder(YogaEdge edge);
+
+  YogaBoxSizing getBoxSizing();
 }