Fix black keyguard / missing status bar

The status bar window was stuck in the READY_TO_SHOW state
because it was not policy visible, whereas the policy
was waiting for the window to become HAS_DRAWN.

Now BarController also updates states if the window
is READY_TO_SHOW, which in turn allows the window to
become visible and HAS_DRAWN.

Bug: 22072099
Change-Id: I1836c276723ee2205d7d5759be079f02aaa23e2e