Use AOD/LS SystemUI clock-specific font

Use a custom variable width font on AOD/LS. Use weight 200 on AOD and weight
400 on LS. The animation currently re-layouts throughout the animation,
and eventually should animate using new TextAPIs.

To toggle on the new lockscreen:
  adb shell settings put global show_new_lockscreen 1

Test: manual
Bug: 170228350
Change-Id: I62072a3e4a045f10606f8c7ed3f5214107e1670d