Migrate app to TypeScript (#1637)

* Initial setup and migrated src/common

* WIP

* WIP

* WIP

* Main module basically finished

* Renderer process migrated

* Added CI step and some fixes

* Fixed remainder of issues and added proper ESLint config

* Fixed a couple issues

* Progress!

* Some more fixes

* Fixed a test

* Fix build step

* PR feedback

webpack.config.base.js

@@ -36,6 +36,7 @@ module.exports = {
             common: path.resolve(__dirname, './src/common'),
             static: path.resolve(__dirname, './src/assets'),
         },
+        extensions: ['.ts', '.tsx', '.js', '.jsx'],
     },
 };