Add support for Windows Dark Mode (#1217)

* Add support for Windows Dark Mode

* Add is_dark_mode() getter to WindowExtWindows

* Add WindowEvent::DarkModeChanged

* Add support for dark mode in Windows 10 builds > 18362

* Change strategy for querying windows 10 build version

* Drop window state before sending event

Co-Authored-By: daxpedda <daxpedda@gmail.com>

* Change implementation of windows dark mode support

* Expand supported range of windows 10 versions with dark mode

* Use get_function! macro where possible

* Minor style fixes

* Improve documentation for ThemeChanged

* Use `as` conversion for `BOOL`

* Correct CHANGELOG entry for dark mode

Co-authored-by: daxpedda <daxpedda@gmail.com>
Co-authored-by: Osspial <osspial@gmail.com>

src/window.rs

@@ -857,3 +857,9 @@ pub enum Fullscreen {
     Exclusive(VideoMode),
     Borderless(MonitorHandle),
 }
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum Theme {
+    Light,
+    Dark,
+}