ComposeClock: Move shade's clock interactor and repository to common dir

Move and rename ShadeHeaderClockInteractor and
ShadeHeaderClockRepository to systemui/clock. This is part of an effort
to create a composable clock that will be used in both the status bar
and the shade.

Bug: 390204943
Flag: com.android.systemui.clock_modernization
Test: ClockInteractorTest, ClockRepositoryTest
Change-Id: I0912e07eaea753ecdce2b34c85e07ba9df81d48a