Window Manager Flag Migration (4/n)

Wire up the appearance and the transient state of system bars between
WMS and System UI. The derived classes of CommandQueue.Callbacks no
longer listen to setSystemUiVisibility, but listen to showTransient,
abortTransient, and onSystemBarAppearanceChanged instead.

Bug: 118118435
Test: atest InsetsSourceProviderTest InsetsStateControllerTest
            InsetsPolicyTest WindowStateTests CommandQueueTest
            RegisterStatusBarResultTest InsetsFlagsTest
            LightBarControllerTest
Change-Id: I1dcaff47ae57ccee91146fdc042cde5e26fc0b3f