Add onActionClicked in NotificationAssistantService

This is added to report clicks on actions buttons to NAS.

BUG: 119010281
Test: atest SystemUITests
Test: atest RemoteViewsTest
Test: atest NotificationManagerServiceTest
Test: Manual. Tapped on the action (both normal and contextual) and
      observed the log.

Change-Id: I381994737d8c3185d3fabf9b6c481fd01a89a634
diff --git a/core/java/android/app/Notification.java b/core/java/android/app/Notification.java
index 75b56f3..cf43f59 100644
--- a/core/java/android/app/Notification.java
+++ b/core/java/android/app/Notification.java
@@ -5434,6 +5434,8 @@
                             ambient ? resolveAmbientColor() : resolveContrastColor());
                 }
             }
+            button.setIntTag(R.id.action0, R.id.notification_action_index_tag,
+                    mActions.indexOf(action));
             return button;
         }