monitor-manager: only support underscan when mode allows it

Underscan should only be available for certain modes; in particular, it
should only be available for HDMI displays with a compatible resolution.

https://bugzilla.gnome.org/show_bug.cgi?id=767804

!549
5 jobs for !549 with gbsneto/underscan in 5 minutes and 10 seconds (queued for 2 seconds)
latest detached
Status Job ID Name Coverage
  Review
passed #339808
check-commit-log

00:00:24

 
  Build
passed #339809
build-mutter

00:01:24

passed #339810
build-without-native-backend

00:02:14

 
  Test
passed #339812
can-build-gnome-shell

00:01:34

passed #339811
test-mutter

00:02:30