Send more IME events to autofill manager service.

* In IME side, wait for the input start before calling back to Autofill,
  rather than returning inline unsupported immediately.
* Also adds an InlineSuggestionManager to simplify code in the
  InputMethodService

Test: atest CtsAutoFillServiceTestCases
Test: atest CtsInputMethodTestCases
Bug: 151123764

Change-Id: I199925d77aa508f259e98a8929120aeb96015b57