It's very useful to have common functions for easily creating a monitor
test setup for all kinds of tests, so move create_monitor_test_setup()
and check_monitor_configuration() and all the structs those are using to
monitor-test-utils.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1243
So far some basic testing, including:
* Test that the migrated configuration is applicable
* Test that a monitors.xml with multiple configurations are translated
* Test rotation
* Test tiled monitor discovery (well, test a made up tiled monitor
configuration since I don't have a real one)
https://bugzilla.gnome.org/show_bug.cgi?id=777732
Both the monitor unit tests and monitor store unit tests will want to
check whether the config manager is used and set custom configuration
files.
https://bugzilla.gnome.org/show_bug.cgi?id=777732
