New APIs for Augmented Autofill whitelisting, plus some spring cleaning...

Test: m update-api # they're not implemented yet
Test: atest CtsAutoFillServiceTestCases:android.autofillservice.cts.augmented.AugmentedLoginActivityTest # for sanity checking

Bug: 123100824
Bug: 111330312
Bug: 123233342

Change-Id: I9f6b9067f743b7590cc8b32b42b8fff230f9a3d8