Move LauncherWidgetHolder to widget package

Making LauncherAppWidgetHost package-private as well

Bug: 235358918
Test: N/A
Change-Id: If022ec8d429579a972991872b2dc11db76719341
diff --git a/src/com/android/launcher3/DefaultLayoutParser.java b/src/com/android/launcher3/DefaultLayoutParser.java
index d8558f0..af13bea 100644
--- a/src/com/android/launcher3/DefaultLayoutParser.java
+++ b/src/com/android/launcher3/DefaultLayoutParser.java
@@ -20,6 +20,7 @@
 import com.android.launcher3.model.data.WorkspaceItemInfo;
 import com.android.launcher3.shortcuts.ShortcutKey;
 import com.android.launcher3.util.Thunk;
+import com.android.launcher3.widget.LauncherWidgetHolder;
 
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;