[core][ios][osx][android] fix icons with non-integer width/height

ref #3031
ref #2198

For example, an icon that has:
- a pixel width of 10
- a pixel ratio of 3
- a scaled with of 3.333
is now supported.

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/views/MapView.java

@@ -2314,8 +2314,8 @@ public final class MapView extends FrameLayout {
 
         mNativeMapView.addAnnotationIcon(
                 id,
-                (int) (bitmap.getWidth() / scale),
-                (int) (bitmap.getHeight() / scale),
+                bitmap.getWidth(),
+                bitmap.getHeight(),
                 scale, buffer.array());
     }