AccessibilityInjector should return false on a failed action.

1. AccessibilityInjector was returning true even if the underlying
   JavaScript was not loaded/failed. This may lead to TalkBack getting
   stuck in a web view. To avoid this TalkBack requires gran1ularity
   change when getting into web view. This is neither advertised nor
   shown in the tutorial and which is worse it is inconsistent with
   the traversal of the app.

   Now if the action fails, false is returned and also the timeout for
   handling the action request is increased to 5s. Upon the completion
   of this timeout TalkBack may decide to show a wait dialog or just
   skip the web content. We are treating this as an ANR.

bug:6663344

Change-Id: Idf3d08fe928c495bb974a127f853de6f938e2f77