Eliminates NotificationEntryManager.getNotificationLongClicker().

This method always returned NotificationGutsManager::openGuts, and only
existed so that CarSystemUI could override it to disable long presses.
In this change we accomplish this by making
NotificationStackScrollLayout injectable and providing a named flag for
whether to enable long presses or not as a dependency.  This means that
NotificationEntryManager is no longer involved in handling long presses,
and CarNotificationEntryManager no longer needs to exist.

Test: atest SystemUITests, manual
Change-Id: Iae78601fea498a37ed47ef9a114e50de1652b6a8
diff --git a/packages/SystemUI/src/com/android/systemui/Dependency.java b/packages/SystemUI/src/com/android/systemui/Dependency.java
index a8d3763..3d2f838 100644
--- a/packages/SystemUI/src/com/android/systemui/Dependency.java
+++ b/packages/SystemUI/src/com/android/systemui/Dependency.java
@@ -157,6 +157,12 @@
     public static final String LEAK_REPORT_EMAIL_NAME = "leak_report_email";
 
     /**
+     * Whether this platform supports long-pressing notifications to show notification channel
+     * settings.
+     */
+    public static final String ALLOW_NOTIFICATION_LONG_PRESS_NAME = "allow_notif_longpress";
+
+    /**
      * Key for getting a background Looper for background work.
      */
     public static final DependencyKey<Looper> BG_LOOPER = new DependencyKey<>(BG_LOOPER_NAME);