API changes for device initialization / SUW

The API changes for device initialization / SetUp Wizard. Besides
removing @hide, this commit deletes some tests (which can now be covered
by CTS) and makes minor doc and annotation updates.

Bug: 236612872
Test: See associated CTS changes
Test: atest core/tests/coretests/src/android/app/time/
Change-Id: I0c99c55e5e4dd339cfd226fc472ba8c8f2cf1d2f