Various Monitor/VideoModeHandle methods now return an Option

`VideoModeHandle::refresh_rate_millihertz()` and `bit_depth()` now return a `Option<NonZero*>`.
`MonitorHandle::position()` now returns an `Option`.
On Orbital `MonitorHandle::name()` now returns `None` instead of a dummy name.

src/platform_impl/windows/window.rs

@@ -786,7 +786,7 @@ impl Window {
                         Fullscreen::Borderless(None) => monitor::current_monitor(window),
                     };
 
-                    let position: (i32, i32) = monitor.position().into();
+                    let position: (i32, i32) = monitor.position().unwrap_or_default().into();
                     let size: (u32, u32) = monitor.size().into();
 
                     unsafe {