Update usages of NotificationSettingsInteractor

Changed the interactor & repository to hold individual settings rather
than one object with all of them. This CL updates the usages, and also
moves the NotificationSettingsRepositoryTest to frameworks/base (see
other CL in topic).

Bug: 293167744
Test: NotificationSettingsRepositoryTest + verified manually that the
lockscreen notif toggle works correctly
Flag: NONE

Change-Id: I108867263f976fa550e08bc9718fac71074a73ce