Disallow windows in multi-window mode turn on screen

Bug: 160925539
Test: atest ActivityRecordTests
Test: Activity that has turnScreenOn and showWhenLocked both true can
turn on screen if launched in fullscreen mode, but can't turn on screen
if launched in freeform mode.

Change-Id: I9693b0adc3db6730c997923f23b784e386f71c99