Update test scripts

- Configured `npm test` to use Jest.
- Added script `npm run watch-test` to run Jest in watch mode.

Author: iamWing

package.json

@@ -7,7 +7,8 @@
     "start": "electron ./dist/main.bundle.js",
     "dev": "rimraf dist && cross-env NODE_ENV=development webpack --watch --progress --color",
     "prod": "rimraf dist && cross-env NODE_ENV=production webpack --progress --color",
-    "test": "mocha -r ts-node/register -r tsconfig-paths/register \"test/**/*.ts\"",
+    "test": "cross-env NODE_ENV=test jest",
+    "watch-test": "npm run test -- --watchAll",
     "build:win": "electron-builder build --win --x64",
     "build:mac": "electron-builder build --mac --x64"
   },