Split autofill InlineSuggestionSession to two classes

* The AutofillInlineSession is renamed from InlineSuggestionSession, to
  avoid confusion from having the same name as the
  inputmethod/InlineSuggestionSession.
* The convoluted synchronization and CompletableFuture are removed to
  simplify the flow and reduce potential bug. Everything requires the
  same mLock as the Session now, so that they are synchronized and
  deadlock-free.
* The AutofillInlineSessionController is introduced, to prepare for the
  follow on patch where we will make each AutofillInlineSession to be
  only responsible for one field.

Test: manual
Test: atest CtsAutoFillServiceTestCases

Bug: 151123764

Change-Id: I92cc558351b57f04553709569b8d41b928b9b49d