Add config for avoiding JNI refs

Summary:
@public

Adds `YogaConfig#avoidGlobalJNIRefs` to control whether nodes created with a config will use weak global JNI refs. Used for experimentation.

Reviewed By: SidharthGuglani

Differential Revision: D14149982

fbshipit-source-id: c777c8b3af2167d96154db5aa6afec1476dac35b

java/com/facebook/yoga/YogaConfig.java

@@ -22,6 +22,7 @@ public class YogaConfig {
   long mNativePointer;
   private YogaLogger mLogger;
   private YogaNodeCloneFunction mYogaNodeCloneFunction;
+  public boolean avoidGlobalJNIRefs = false;
 
   private native long jni_YGConfigNew();
   public YogaConfig() {