Decrease TAPL All Apps scrolling flakiness

scrolling in all apps did not factor in additional top padding in the all apps list recycler. This made it so that apps could occasionally scroll and be obcured by that top padding, making them un-tappable. Added this padding to the scrolling logic to make scrolling less flaky.

Test: TaplTestsTaskbar, TaplTestsLauncher3 and presubmit
Fixes: 248064856
Change-Id: Id76b92b4bc354917f3688ac53673d0ed7a905f02

quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsController.java

@@ -16,6 +16,7 @@
 package com.android.launcher3.taskbar.allapps;
 
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 
 import com.android.launcher3.R;
 import com.android.launcher3.appprediction.PredictionRowView;
@@ -123,4 +124,11 @@ public final class TaskbarAllAppsController {
                 .findFixedRowByType(PredictionRowView.class)
                 .setPredictedApps(mPredictedApps);
     }
+
+
+    @VisibleForTesting
+    public int getTaskbarAllAppsTopPadding() {
+        // Allow null-pointer since this should only be null if the apps view is not showing.
+        return mAppsView.getActiveRecyclerView().getClipBounds().top;
+    }
 }