Refactor FolderIcon to separate the preview effect into it's own class

-> Created com.android.launcher3.folder package to house most folder-related files
   (aside from the FolderInfo) which is more related to the model than the UI.

Change-Id: I767063e1e4c775c01a799a3bede30cd94ac48ade
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 414ebb4..545768f 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -107,6 +107,8 @@
 import com.android.launcher3.dragndrop.DragController;
 import com.android.launcher3.dragndrop.DragLayer;
 import com.android.launcher3.dragndrop.DragView;
+import com.android.launcher3.folder.Folder;
+import com.android.launcher3.folder.FolderIcon;
 import com.android.launcher3.model.WidgetsModel;
 import com.android.launcher3.util.ComponentKey;
 import com.android.launcher3.util.LongArrayMap;
@@ -366,7 +368,7 @@
     }
 
     private Stats mStats;
-    FocusIndicatorView mFocusHandler;
+    public FocusIndicatorView mFocusHandler;
     private boolean mRotationEnabled = false;
 
     @Thunk void setOrientation() {