Some cleanup for SwipeDetector.

It is now organized as follows:
 - private constants
 - public constants
 - private final fields
 - private variable fields
 - constructors
 - public methods
 - private methods
 - public interface/abstract class

This is intended to be a functional no-op.

Bug: 141939911
Change-Id: Iad5a9b3b73b35641f8a4f1d52ada6adef3825c47
Tested: Built and sanity checked manually.

src/com/android/launcher3/notification/NotificationItemView.java

@@ -16,6 +16,8 @@
 
 package com.android.launcher3.notification;
 
+import static com.android.launcher3.touch.SwipeDetector.HORIZONTAL;
+
 import android.app.Notification;
 import android.content.Context;
 import android.graphics.Color;
@@ -33,8 +35,6 @@ import com.android.launcher3.util.Themes;
 
 import java.util.List;
 
-import static com.android.launcher3.touch.SwipeDetector.HORIZONTAL;
-
 /**
  * Utility class to manage notification UI
  */