Support borders in RCTImageView

Summary: @public Initial RCTImageView implementation only supported 'src', 'tintColor' and 'resizeMode'. This diff adds support for the rest of the properties: 'borderColor', 'borderWidth' and 'borderRadius'. `AbstractDrawBorders` class is reused in a follow up diff to draw borders for 'RCTView'.

Reviewed By: sriramramani

Differential Revision: D2693560

ReactAndroid/src/main/java/com/facebook/react/flat/BitmapRequestHelper.java

@@ -107,6 +107,10 @@ import com.facebook.infer.annotation.Assertions;
     return ((CloseableBitmap) closeableImage).getUnderlyingBitmap();
   }
 
+  /* package */ boolean isDetached() {
+    return mAttachCounter == 0;
+  }
+
   @Override
   public void onNewResult(DataSource<CloseableReference<CloseableImage>> dataSource) {
     if (!dataSource.isFinished()) {