Show HUN layout on lockscreen when FSI permission is denied

Bug: 271358296
Test: visual
  deny FSI permission, send HUN on lockscreen
  => show heads up layout

  send multiple HUNs on lockscreen
  => all HUNS show heads up layout

  send HUN with UMO at default display size, font size
  => show as icon in shelf when there's not enough space

  press HUN's expand button to go to full shade
  => show expanded layout with emphasized buttons (no regression)

  send HUN while pulsing/unlocked
  => show HUN layout with emphasized buttons (no regression)

Test: ExpandableNotificationRowTest
Test: NotificationStackSizeCalculatorTest
Change-Id: I2394fad0b7cd78c2f38be26d90e61152385dd63c