[apps] Add Shift + Ans shortcut to go to the last application

apps/apps_container_storage.cpp

@@ -36,3 +36,18 @@ App::Snapshot * AppsContainerStorage::appSnapshotAtIndex(int index) {
   assert(index >= 0 && index < k_numberOfCommonApps);
   return snapshots[index];
 }
+
+// Get the index of the app from its snapshot
+int AppsContainerStorage::appIndexFromSnapshot(App::Snapshot * snapshot) {
+  App::Snapshot * snapshots[] = {
+    homeAppSnapshot()
+    APPS_CONTAINER_SNAPSHOT_LIST
+  };
+  assert(sizeof(snapshots)/sizeof(snapshots[0]) == k_numberOfCommonApps);
+  for (int i = 0; i < k_numberOfCommonApps; i++) {
+    if (snapshots[i] == snapshot) {
+      return i;
+    }
+  }
+  return NULL;
+}