Take screen-off animation into account when determining hiding nav bar

- When the keyguard hides the nav bar, take into account the screen-off
  animation so that we can hide it earlier when the animation starts

Bug: 190368572
Test: atest StatusBarKeyguardViewManagerTest
Test: In three button nav w/ AOD, turn off the screen
      - also try above with interrupting the screen off animation
      - also try above with power button instantly locks disabled
Change-Id: I504cd55e243976586b0544100e46d2b14fa33850