Add letter spacing setting for the lockscreen preview

The letters should be more close.

Screenshot:
  - Lockscreen: https://screenshot.googleplex.com/AbYy29ZAmHqc6Ka.png
  - Before: https://screenshot.googleplex.com/99mKbtr3xQUY6Am.png
  - After: https://screenshot.googleplex.com/CjevNqGzK94aBEw.png

Bug: 179341439
Test: manual
Change-Id: I317f0cc1f1b322d3eb612fcb5e76dce12aa79807
1 file changed