Move selection to selection pkg, make activity scoped.

Move all other selection related classes to selection pkg.

Change-Id: I57a3964fada55b0f4d073f05a7833455235221b9
diff --git a/src/com/android/documentsui/dirlist/UserInputHandler.java b/src/com/android/documentsui/dirlist/UserInputHandler.java
index cc9a81f..4af1fcd 100644
--- a/src/com/android/documentsui/dirlist/UserInputHandler.java
+++ b/src/com/android/documentsui/dirlist/UserInputHandler.java
@@ -28,6 +28,7 @@
 import com.android.documentsui.base.EventHandler;
 import com.android.documentsui.base.Events;
 import com.android.documentsui.base.Events.InputEvent;
+import com.android.documentsui.selection.SelectionManager;
 
 import java.util.Collections;
 import java.util.function.Function;
@@ -46,7 +47,7 @@
 
     private ActionHandler mActionHandler;
     private final FocusHandler mFocusHandler;
-    private final MultiSelectManager mSelectionMgr;
+    private final SelectionManager mSelectionMgr;
     private final Function<MotionEvent, T> mEventConverter;
     private final Predicate<DocumentDetails> mSelectable;
 
@@ -63,7 +64,7 @@
     public UserInputHandler(
             ActionHandler actionHandler,
             FocusHandler focusHandler,
-            MultiSelectManager selectionMgr,
+            SelectionManager selectionMgr,
             Function<MotionEvent, T> eventConverter,
             Predicate<DocumentDetails> selectable,
             EventHandler<InputEvent> rightClickHandler,