Add support for custom scale types

Summary:
public
This diff adds support for providing custom scaletypes to Drawee. The implementation for the preexisting scale types is preserved.
Breaking changes should be minimal. In fact, only direct usages of `ScalingUtils.getTransform(..., scaleType)` should be converted to `scaleType.getTransform(...)`.

Reviewed By: kirwan

Differential Revision: D2862911

fb-gh-sync-id: ab0355fd13544dc08ce4481eda87287404ea7adb

ReactAndroid/src/main/java/com/facebook/react/views/image/ReactImageView.java

@@ -74,16 +74,15 @@ public class ReactImageView extends GenericDraweeView {
   private class RoundedCornerPostprocessor extends BasePostprocessor {
 
     float getRadius(Bitmap source) {
-        ScalingUtils.getTransform(
-            sMatrix,
-            new Rect(0, 0, source.getWidth(), source.getHeight()),
-            source.getWidth(),
-            source.getHeight(),
-            0.0f,
-            0.0f,
-            mScaleType);
-        sMatrix.invert(sInverse);
-        return sInverse.mapRadius(mBorderRadius);
+      mScaleType.getTransform(
+          sMatrix,
+          new Rect(0, 0, source.getWidth(), source.getHeight()),
+          source.getWidth(),
+          source.getHeight(),
+          0.0f,
+          0.0f);
+      sMatrix.invert(sInverse);
+      return sInverse.mapRadius(mBorderRadius);
     }
 
     @Override