Add MPRIS support (#25)

* Stop mpv on app close for linux/macOS (#20)

* Add initial MPRIS support

* Fix mpv path check

src/main/preload/utils.ts

@@ -0,0 +1,7 @@
+import { isMacOS, isWindows, isLinux } from '../utils';
+
+export const utils = {
+  isLinux,
+  isMacOS,
+  isWindows,
+};