dock: fix DockObserver initialization with WM

- Now ActivityManager is not ready when WM initializes. DockObserver
  also starts later, the sticky intent will not exist.
- Introduces a new local service for DockObserver so that
  WindowManagerPolicy can read the dock state before ActivityManager is
  ready.
- Fix logging, it was never logged properly.

Bug: 383531830
Test: manual
Flag: EXEMPT, bug fix
Change-Id: I5da6f8005d6d9fbf3962e1c1262b0a3e65b09439