output: Move configureable state to instance private

That is is_presentation, is_primary, is_underscanning and backlight.

The first three are set during CRTC assignment as they are only valid
when active. The other is set separately, as it is untied to
monitor configuration.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1287

src/backends/meta-monitor-manager-private.h

@@ -387,4 +387,22 @@ gboolean meta_monitor_has_aspect_as_size (MetaMonitor *monitor);
 char * meta_monitor_manager_get_vendor_name (MetaMonitorManager *manager,
                                              const char         *vendor);
 
+static inline MetaOutputInfo *
+meta_find_output_info (MetaOutputInfo **outputs,
+                       unsigned int     n_outputs,
+                       MetaOutput      *output)
+{
+  unsigned int i;
+
+  for (i = 0; i < n_outputs; i++)
+    {
+      MetaOutputInfo *output_info = outputs[i];
+
+      if (output == output_info->output)
+        return output_info;
+    }
+
+  return NULL;
+}
+
 #endif /* META_MONITOR_MANAGER_PRIVATE_H */