Optimize sysui ui queue during keyguard unlock.

Target the two biggest offenders:
 - Coalesce keyguard setHidden(false) calls during unlock.
 - Make sysui->WM call async.

Found during investigation into b/11221659.

Bug: 11221659
Change-Id: Icab48376bc356a933e0f9940bc2f924e2e77ab22