Make Clock options resettable (1/3)

Moved `ClockPickerSnapshotRestorer` to `ThemePicker`.

`ClockPickerSnapshotRestorer` creates snapshots based on `ClockOptionModel` which contains all clock related options. The original snapshot created from the latest options in the repository, after user made a change, the snapshot is created from the repository and override with the change, this is to prevent race condition where the change has not been written in the `SecureSettings`.

Bug: 274403822
Test: play with Clock options
Change-Id: Ia5475e3b367604b96a3dc6533c4cdbacc1f1fcb5