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.

modules/icons/index.ts

@@ -196,4 +196,4 @@ export default {
         patchy_light_snow_with_thunder: "weather-snow-symbolic",
         moderate_or_heavy_snow_with_thunder: "weather-snow-symbolic",
     },
-};
+} as const;