Added strict type checking to the project. (#236)

* Implement strict typing (WIP).

* changes

* Finish type checks

* Fix notification icon, matugen settings and update tsconfig.

* OSD Styling updates and added the ability to configure OSD duration.

lib/types/mpris.d.ts

@@ -0,0 +1,3 @@
+export type LoopStatus = 'none' | 'track' | 'playlist';
+export type PlaybackStatus = 'playing' | 'paused' | 'stopped';
+