[Relayout] Part 3: Introduce more functionality[Relayout]

Add in functionality to find all autofillable views.
This is useful when relayout happens, and we need to find
all autofillable views without having an autofill request
trigger, or assist structure generated.

Bug: 238252288
Flag: EXEMPT : DeviceConfig flags used: enable_relayout
exception granted in b/318391032
Test: atest CtsAutoFillServiceTestCases
      atest FrameworksCoreTests:ViewGroupTest

Change-Id: Iae0f5ec10cd17c9524ff2567a5a8cb0c7a0c1775