Notify autofill with the IME start/finish input view events

* autofill will cache the inline suggestions response until it receives
  a start input view event from IME
* the data flow from IMS point of view is:
  IMS#startViews and IMS#doStartInput (before calling onStartInputView)
  ->
  [async] InlineSuggestionsRequestCallback#onInputMethodStartInputView()
  --- process boundary ---
  ->
  IMMS.InlineSuggestionsRequestCallbackDecorator
     #onInputMethodStartInputView()
  ->
  InlineSuggestionSession.InlineSuggestionsRequestCallbackImpl
     #onInputMethodStartInputView()
* similar data flow for  IMS#finishViews()
* this CL should not block IME's UI thread because it's only issuing a
  new async IPC from IMS start/finish input view call that's running on
  the UI thread.
* there should not be performance impact on IMEs if autofill inline
  integration is not active

Test: manual verification, atest EditorInfoTest
Test: atest android.autofillservice.cts.inline, with two failing cases:
 InlineAugmentedLoginActivityTest#testAugmentedAutoFill_twoDatasetThenFilledSecond
 and InlineAugmentedLoginActivityTest#testAugmentedAutoFill_oneDatasetThenFilled
 due to the test itself being broken, I'll fix the test in a separate patch
Bug: 149522488
Bug: 149442582
Change-Id: I2faa3577b9f95a122f26a6d7fa7822a769a51e34