Create InlineAction class to wrap the IntentSender and the presentation

* Before this change, we were putting the action intent in the Slice,
  but we realize that's not the best place as slice is only meant for
  data representation, and intent does not fall into that
* This patch includes the code to actually fire the pending intent when
  action suggestion is clicked. However, it'll only work if the fill
  service have the SYSTEM_ALERT_WINDOW permission for the intent to
  be fired when it is in the background. We will move it to be fired
  from the client foreground app in a separate patch

Test: manual verification
Test: atest android.autofillservice.cts.inline
Bug: 150499490

Change-Id: I411a7ee05e783f7de94a54064c44a6126afe0b12