Add an event type constant for Undismiss events when the user clicks

Undo after dragging a predicted app icon onto the "Do Not Suggest" drop
target.

Bug: b/200841778
Test: Verified that the constant was usable from Launcher project.
Change-Id: I0f7e4f139a7b9012fd55bf72294dd8c1fab38a39

core/api/system-current.txt

@@ -1928,6 +1928,7 @@ package android.app.prediction {
     field public static final int ACTION_DISMISS = 2; // 0x2
     field public static final int ACTION_LAUNCH = 1; // 0x1
     field public static final int ACTION_PIN = 3; // 0x3
+    field public static final int ACTION_UNDISMISS = 5; // 0x5
     field public static final int ACTION_UNPIN = 4; // 0x4
     field @NonNull public static final android.os.Parcelable.Creator<android.app.prediction.AppTargetEvent> CREATOR;
   }

core/java/android/app/prediction/AppTargetEvent.java

@@ -60,6 +60,11 @@ public final class AppTargetEvent implements Parcelable {
      */
     public static final int ACTION_UNPIN = 4;
 
+    /**
+     * Event type constant indicating an app target has been un-dismissed.
+     */
+    public static final int ACTION_UNDISMISS = 5;
+
     private final AppTarget mTarget;
     private final String mLocation;
     private final int mAction;