Add pango_font_get_face

Since we've run out of slots in PangoFontClass,
this is implemented with a vfunc in PangoFontMapClass.
3 jobs for family-face-api in 4 minutes and 14 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #391123
gnome-runtime-linux

00:02:08

passed #399153
win32
msys2-mingw64

00:02:05

failed #391124
win32
msys2-mingw64

00:05:53