Add three display/body font overlays.

Note that these overlays can be checked in before b/122043381 since the
system fallback font is used if not installed on the device. The theme
picker should verify whether the REQUIRED_SYSTEM_FONTS listed in the
overlay meta-data are present before exposing these as font options.

Bug: 118756857
Test: manually toggling these overlays
Change-Id: I8ac544436eac5f7d16803c7b1c2580499adbe0c8