Create common superclass for old and new provider tests

This does not yet test the legacy suppressor interface; that will come
in a later CL.

Bug: 261728888
Test: atest NotificationInterruptStateProviderWrapperTest
Flag: none needed, not instantiated yet
Change-Id: Iacc17ab6461cb02f4ed62965e2ae7bce097692c5
5 files changed